Add remote IMAP search support.

* rbayer/IMAPsearch: (21 commits)
  More cleanup
  Code Cleanup getRemoteSearchFullText -> isRemoteSearchFullText line wraps for preference items
  Refactor to allow fetching of extra search results beyond original request.  Most code moved out of ImapStore and ImapFolder and into MessagingController.searchRemoteMessagesSynchronous.  Should make it easier to add remoteSearch for other server types.
  Prevent delete of search results while search results open
  remove duplicated code block
  Don't hide Crypto when IMAPsearch disabled
  Code Style Cleanup: Tabs -> 4 spaces Remove trailing whitespace from blank lines
  tabs -> spaces (my bad...)
  Fix opening of folders to be Read-Write when necessary, even if they were previously opened Read-Only.
  add missing file
  Working IMAP search, with passable UI.
  UI improvements
  Simple help info when enabling Remote Search
  Dependency for preferences
  Basic IMAP search working
modified loadMessageForView() to dowload message if neither X_DOWNLOADED_FULL nor X_DOWNLOADED_PARTIAL.
IMAP Search: log exceptions on remote search, properly dispatch MessageList changes.
Add remote search actionbar icons.
Whitespace fix; no functional changes.
Handle implicit vs. explicit searches in ActionBar home button behavior.
Whitespace; no functional changes.
Add settings export for remote search settings.
Log remote search exceptions in addition to toasting them.
Add cloud search icon to local search result screen. Implement pull-to-remote-search.
changed PREFERENCE_CLOUD_SEARCH_ENABLED from "cloud_search_enabled" to "remote_search_enabled" in
activity/setup/AccountSettings.java to resolve FC.
Rename variables
Remove duplicate notification on remote search start.
Move IMAP search into the Folder level.

Should also consider moving the LocalStore search into the folder level and have the store call the folder level searches.
Handle aborted imap searches by nuking in-progress connections.
Change settings version to 18 to match what's currrently on master.
Merge branch 'imapsearch'

* imapsearch:
  Change settings version to 18 to match what's currrently on master.
  Handle aborted imap searches by nuking in-progress connections.
  Move IMAP search into the Folder level.
  Remove duplicate notification on remote search start.
  Rename variables
  changed PREFERENCE_CLOUD_SEARCH_ENABLED from "cloud_search_enabled" to "remote_search_enabled" in activity/setup/AccountSettings.java to resolve FC.
  Add cloud search icon to local search result screen. Implement pull-to-remote-search.
  Log remote search exceptions in addition to toasting them.
  Add settings export for remote search settings.
  Whitespace; no functional changes.
  Handle implicit vs. explicit searches in ActionBar home button behavior.
  Whitespace fix; no functional changes.
  Add remote search actionbar icons.
  IMAP Search: log exceptions on remote search, properly dispatch MessageList changes.
  modified loadMessageForView() to dowload message if neither X_DOWNLOADED_FULL nor X_DOWNLOADED_PARTIAL.
  Add remote IMAP search support.

Conflicts:
	res/menu/message_list_option.xml
	res/values/attrs.xml
	res/values/themes.xml
	src/com/fsck/k9/activity/MessageList.java
	src/com/fsck/k9/preferences/Settings.java