Move vendor/Joomla to src/Joomla. Update necessary paths.
Exclude some files we only need in the repository from the ZIP files generated by GitHub.
Fixes a number of issues in the Input pacakge.

Fixed the mocker to proxy `get`, `post` and `request` variables better.
Fixed a problem in the Json input class where the internal data can be
set to `null`.
Exclude `vendor/psr` from the git index.
Fixed typos
Update Input Mocker

Renames mocker class to `InputMocker`.
Added support for `Json` input.
Updated docs.
Fixing stuff after move.
Code cleanup based on PhpStorm inspector
Add composer installation instructions to each package. Closes #13
Make the package unit tests run really standalone.