Remove Actions Utility Methods

As per https://github.com/ReactiveX/RxJava/issues/1799
Remove `Not` Class

As per https://github.com/ReactiveX/RxJava/issues/1798
Merge pull request #1806 from benjchristensen/remove-utilities

Remove Unnecessary Utilities
Remove Javadoc Linebreaks
Remove Utility Functions from Public API

Fixes https://github.com/ReactiveX/RxJava/issues/1797
Merge pull request #1809 from benjchristensen/1797-utility-functions

Remove Utility Functions from Public API