implemented OperationDematerialize
added dematerialize api to observable
unit test for OperationDematerialize
updated dematerialize unit tests to use mockit
optimize imports
Merge branch 'dematerialize' of git://github.com/prabirshrestha/RxJava into dematerialize-merge

- added Javadoc for @throws Exception
- suppressed unchecked warnings

Conflicts:
	rxjava-core/src/main/java/rx/Observable.java
Merge pull request #177 from benjchristensen/dematerialize-merge

Operator: Dematerialize - review and manual merge