Update README.markdown

Added sections about contributing and getting commit access
Update README.markdown

Added steps for building with Xcode 5 against 10.5 SDK
Revert "Changed open sheet to use file extensions instead of UTIs becaused it was causing problems with m4v extension"

This reverts commit 04ffaf60264cd04592aca1e3b941d9d0cae30894.
Removed output of extensions when showing open sheet
Started using PlistBuddy instead of defaults to read values from plist file in scripts
Moved shell scripts to Scripts folder
Changed the UTI conform to requirement to kUTTypeAudiovisualContent so that we also support audio
Moved document types information to data provider plugin
Moved private MZPlugin category to main source file
Refactored so that MZScriptActionsPlugin does not have a bundle assigned
Removed unused old dataProviders and searchProviders methods from MZPlugin
Changed plugin label so that it checks the bundle for a CFBundleDisplayName and a CFBundleName key in Info.plist
Added accessors for plugin types that include disabled plugins
Bumped version to 1.0a14
Removed Test-Info.plist
Added version number to settings
Updated project to Xcode 5
Added init script to simplify build from fresh checkout
Fixed error caused by implicit conversion to CGRect.