Corrected help activity naming to `HelpActivity`.

Fixes #2015
Merge pull request #2017 from wordpress-mobile/issue/2015-preference-activity-name

Corrected help activity naming to `HelpActivity`.
3.4 - 150 - version code bump
Merge branch 'release/3.4' into release/3.5

Conflicts:
	WordPress/build.gradle
	WordPress/src/main/res/xml/settings.xml
	WordPress/src/zbetagroup/res/xml/preferences.xml
3.5-beta-2 version bump