Add newline to end of file
Add .DS_Store to gitignore
Add support for usage in App Extensions

When using PureLayout in an App Extension, define the preprocessor macro PURELAYOUT_APP_EXTENSIONS in the Build Settings of your App Extension's target to prevent usage of unavailable APIs.

Fixes #30
Bump version number and update podspec
Remove some unused imports
Update travis.yml
Return array of created constraints from -autoCreateConstraintsWithoutInstalling:

Enhance the -autoCreateConstraintsWithoutInstalling: API on UIView/NSView to return an array of all the constraints that were created (but not installed) from calls to the PureLayout API inside of the block.
This is particularly useful since any constraints in the block must be captured and stored somewhere, otherwise they will be immediately released (since they are not retained anywhere else).
Add new demo for creating constraints without installing
Update README
Add API to set the views in an array to a size
Improve indentation for preprocessor directives
Added some tests for autoDistribute methods
Slightly refactored horizontal distribution tests and added more test values
Added tests for vertical spacing
Added more test cases to distributing vertically
More tests for fixed size added
Added tests for distributing vertically with fixed size and simplified helper assert methods