Removed forums for beta release.

...st/java/org/briarproject/ForumSharingIntegrationTest.java

...rg/briarproject/ForumSharingIntegrationTestComponent.java

...est/java/org/briarproject/MessageSizeIntegrationTest.java

...org/briarproject/MessageSizeIntegrationTestComponent.java

briar-android/AndroidManifest.xml

briar-android/res/drawable/forum_item_create_white.xml

briar-android/res/layout/activity_available_forums.xml

briar-android/res/layout/activity_create_forum.xml

briar-android/res/layout/activity_share_forum.xml

briar-android/res/layout/fragment_forum_list.xml

briar-android/res/layout/list_item_available_forum.xml

briar-android/res/layout/list_item_forum.xml

briar-android/res/layout/list_item_forum_invitation_in.xml

briar-android/res/layout/list_item_forum_invitation_out.xml

briar-android/res/layout/navigation_menu.xml

briar-android/res/layout/share_forum_message.xml

briar-android/res/layout/text_avatar_view.xml

briar-android/res/menu/forum_actions.xml

briar-android/res/menu/forum_list_actions.xml

briar-android/res/menu/forum_share_actions.xml