Packerlicious

FEATURES:
* builder/Alicloud: add support for packer's alicloud ecs builder
* builder/AmazonInstance: add support for packer's amazon instance builder
* builder/Azure: add support for packer's azure builder
* builder/CloudStack: add support for packer's cloudstack builder
* builder/DigitalOcean: add support for packer's digital ocean builder
* builder/GoogleCompute: add support for packer's google compute builder
* builder/HyperV: add support for packer's hyperv iso builder
* builder/Null: add support for packer's null builder
* builder/OneAndOne: add support for packer's oneandone builder
* builder/OpenStack: add support for packer's openstack builder
* builder/ProfitBricks: add support for packer's ProfitBricks builder
* builder/Qemu: add support for packer's qemu builder
* builder/Triton: add support for packer's triton builder
* builder/VirtualboxIso: add support for packer's virtualbox iso builder
* builder/VirtualboxOvf: add support for packer's virtualbox ovf builder
* builder/VMwareIso: add support for packer's vmware iso builder
* builder/VMwareVmx: add support for packer's vmware vmx builder

FEATURES:
* provisioner/ChefClient: add support for packer's chef client provisioner
* provisioner/ChefSolo: add support for packer's chef solo provisioner
* provisioner/Converge: add support for packer's converge provisioner
* provisioner/PowerShell: add support for packer's powershell provisioner
* provisioner/PuppetMasterless: add support for packer's puppet masterless provisioner
* provisioner/PuppetServer: add support for packer's puppet server provisioner
* provisioner/WindowsShell: add support for packer's windows shell provisioner
* provisioner/WindowsRestart: add support for packer's windows restart provisioner

BUG FIXES:
* fix variable reference logic

OTHER:
* update test coverage

BUG FIXES:
* fix failing builds. Switch travis-ci to use tox, disable python3 builds for now

OTHER:
* update descriptions in setup.py
* add copyright header to py files

FEATURES:
* builder/AmazonEbs: add support for packer's amazon ebs builder
* builder/docker: add support for packer's docker builder
* builder/file: add support for packer's file builder
* post_processor/Alicloud import: add support for packer's Alicloud import post-processor
* post_processor/AmazonImport: add support for packer's amazon import post-processor
* post_processor/Artifice: add support for packer's artifice post-processor
* post_processor/Atlas: add support for packer's atlas post-processor
* post_processor/Checksum: add support for packer's checksum post-processor
* post_processor/Compress: add support for packer's compress post-processor
* post_processor/DockerImport: add support for packer's docker import post-processor
* post_processor/DockerPush: add support for packer's docker push post-processor
* post_processor/DockerSave: add support for packer's docker save post-processor
* post_processor/DockerTag: add support for packer's docker tag post-processor
* post_processor/GoogleComputeExport: add support for packer's google compute image exporter post-processor
* post_processor/Manifest: add support for packer's manifest post-processor
* post_processor/ShellLocal: add support for packer's shell local post-processor
* post_processor/Vagrant: add support for packer's vagrant post-processor
* post_processor/VagrantCloud: add support for packer's vagrant cloud post-processor
* post_processor/VSphere: add support for packer's vsphere post-processor
* provisioner/Ansible: add support for packer's ansible provisioner
* provisioner/AnsibleLocal: add support for packer's ansible local provisioner
* provisioner/File: add support for packer's file provisioner
* provisioner/SaltMasterless: add support for packer's salt masterless provisioner
* provisioner/Shell: add support for packer's shell provisioner
* provisioner/ShellLocal: add support for packer's shell local provisioner