Feature/container cleanup

[allejo]

Summary

Q	A
Bug fix?	yes
New feature?	yes
BC breaks?	no
Deprecations?	no
Fixed issues	N/A

Description

So this branch incorporated more than I originally intended. Here's the rundown:

• Fixes the non-BC change of how Content Items can be accessed from Twig
• Removes the watch command from core; this will be replaced with a separate project
• The internal Service class uses a bitwise sum of flags stakx has set at runtime
• The main Website class has been cleaned up
• Fixes basename and filename variables not being available in FrontMatter
• stakx can be built as a PHAR once again by bundled a pre-built container
• Our Container is no longer passed unnecessarily and is no longer stored in the .stakx-cache folder
• Fixes ContentItems not passing through our template engine

Check List

• [ ] Added appropriate PhpDoc for modifications
• [x] Added unit test to ensure fix works as intended