Ansible-taskrunner

* Accounting for pypi package context for cli invocation logic [975d7a7](https://github.com/berttejeda/ansible-taskrunner/commit/975d7a74c27e534eb1994d2fa48af846c9763410)

* Added additional unit tests for the 'run' subcommand [cbb0607](https://github.com/berttejeda/ansible-taskrunner/commit/cbb06071719681c96fd50cfebc5e0dac781d9792)
* Moved pre-execution cli invocation logic to separate module [3e5d717](https://github.com/berttejeda/ansible-taskrunner/commit/3e5d717ef92b4d32496a5631f4cc6691cf4ebcf8)
* Fixed bug in Taskfile override logic [d825325](https://github.com/berttejeda/ansible-taskrunner/commit/d825325a1b69ee76b8d7d501f8448effdee6e9f3)

* Skip mutually exclusive cli options with broken associations [ebe1cb4](https://github.com/berttejeda/ansible-taskrunner/commit/ebe1cb4440c2d7c5915db42ca6a28f677f12733b)
* Main CLI interface now lends itself to unit/integration tests using click.testing [fbc6cf7](https://github.com/berttejeda/ansible-taskrunner/commit/fbc6cf717b4898d899eb128d9372643c292a7290)

* Fixed bug whereby built-in options weren't properly accounted for in the py2 cli reordering logic [be21143](https://github.com/berttejeda/ansible-taskrunner/commit/be21143552bb11c225452e16dd14aa950c5dbeb1)

* Implement simple string templating for cli options and help-related messages [751fa5e](https://github.com/berttejeda/ansible-taskrunner/commit/751fa5e8bc63c7f7bd8fe0ac97dfec13bdf7be94)

* Added error handling for variable interpolation [1cc2803](https://github.com/berttejeda/ansible-taskrunner/commit/1cc2803e22b83341a0d54503a89dfa8c3114c5f6)
* Added init actions for sftp settings file [8a7dc85](https://github.com/berttejeda/ansible-taskrunner/commit/8a7dc8534d05f99aa4894655fab0841cb826e9d5)