Watchmaker

**Summary**:

* Updates documentation to install pip using `ensurepip` module instead of external
`get-pip.py`
* ash-linux-formula
- Adds pillar option to set content for `/etc/issue` login banner
* join-domain-formula
- (Linux) Adds pillar option to pass a list of domains to add to the trust
list

**Summary**:

* join-domain-formula
- Corrects regression on Windows to support adding admin groups that have
spaces in the name

**Summary**:

* Fixes Python 2.6 incompatibility introduced by new version of PyYAML
* join-domain-formula
- Fixes issue adding admin groups/users to Windows systems with recent versions of Salt

**Summary**:

* Adds additional documentation to answer common EL7 security scan findings
* ash-linux-formula
- Implements additional Salt states to address security scan issues
- Capability to manage GRUB password configuration
- IgnoreRhosts setting in SSH daemon configuration
- CIS remediation handlers ( CIS 5.2.3, CIS 5.2.5)
- Adds Salt state to update audit-rule changes without a system reboot
* scap-formula
- Updates SCAP Security Guide content to v0.1.41

**Summary**:

* amazon-inspector-formula
- New salt formula distributed with watchmaker
- Installs amazon-inspector agent
* Refactor watchmaker
- Change naming mechanism from LinuxManager to LinuxPlatformManager
- Change naming mechanism from WindowsManager to WindowsPlatformManager
- Change naming mechanism from Manager to PlatformManager
- Added abstract class WorkerBase for Workers to inherit from
* ash-linux-formula
- Change ipv6 check to use if_inet6 file
- Import correct source of fopen function
- Configure Postfix to only use ipv4 when ipv6 is disabled

**Summary**:

* ash-windows-formula
- Corrects yaml syntax error in win2016 DC baseline