Update codequality/checkstyle.xml

Removing as it appears to no longer be available in the latest version of checkstyle that comes with gradle 1.4
Upgrading to Gradle 1.4
Switching to bintray for dependencies (same as Maven Central)
Move gradle-release dependency to bintray
Use newer version of license-gradle-plugin that fixes skipExistingHeaders field
Add sonatype snapshot repository
Using latest features of release plugin
Upgrading release process
Matching wrapper to 1.5
Automatically aggregate and publish docs (java,groovy,scala)
Make uploadMavenCentral task, that encompasses other tasks
Handle unavailable sonatype properties
Verify before we can't take it back, use preferredVersion variable
Passing status to Artifactory builds
Created and wired an implementation for the throttle operation on Observables.
Ensure static star imports are used for test cases.
No longer using Notification<T> for scheduling throttled events.
Cleaned up imports and removed unnecessary final keywords in the OperationThrottle class.
Fixed a typo the UnitTest class of OperationThrottle.
Improved key press observable to filter out events of type KEY_TYPED completely.