Added a hook to wait for the DB without waiting for plugins to load.

briar-android/src/net/sf/briar/android/BriarService.java

...-android/src/net/sf/briar/android/HomeScreenActivity.java

...-android/src/net/sf/briar/android/blogs/BlogActivity.java

...roid/src/net/sf/briar/android/blogs/BlogListActivity.java

...src/net/sf/briar/android/blogs/ConfigureBlogActivity.java

...id/src/net/sf/briar/android/blogs/CreateBlogActivity.java

...d/src/net/sf/briar/android/blogs/ManageBlogsActivity.java

.../src/net/sf/briar/android/blogs/ReadBlogPostActivity.java

...src/net/sf/briar/android/blogs/WriteBlogPostActivity.java

...src/net/sf/briar/android/contact/ContactListActivity.java

...c/net/sf/briar/android/groups/ConfigureGroupActivity.java

.../src/net/sf/briar/android/groups/CreateGroupActivity.java

...ndroid/src/net/sf/briar/android/groups/GroupActivity.java

...id/src/net/sf/briar/android/groups/GroupListActivity.java

...src/net/sf/briar/android/groups/ManageGroupsActivity.java

...rc/net/sf/briar/android/groups/ReadGroupPostActivity.java

...c/net/sf/briar/android/groups/WriteGroupPostActivity.java

...net/sf/briar/android/identity/CreateIdentityActivity.java

...c/net/sf/briar/android/invitation/AddContactActivity.java

...c/net/sf/briar/android/messages/ConversationActivity.java