organize all changes
fix a small bug, change android-19 to android-17
DataManager: return empty list when account has no repos
When an account has not repos, the user should get info about it
in the GUI.
Currently, the DataManager returns null in that case, and then the
GUI display message about error fetching repos.
So change the DataManager to return empty list of repos in this case,
and then the GUI displays message that there are no libraries yet.
BrowserActivity: handle case where no path is returned for file to upload

When the user chooses the "Other" upload method, and then selects an image,
the path will be null, and it will cause a nullpointer in BrowserActivity.
Rudimentary avoid this NPE by showing a message to the user, and log it.
SeafileObserver: Remove files from watched and recent lists

After a file is no longer recent, it should be removed from the recent downloaded list,
to avoid that list growing forever larger.
When a file has been removed from the device, it should no longer be in the list of
watched files, to avoid that list growing forever larger.
made some small changes and thanks to Alf Høgemark's advice
Merge pull request #85 from alfh/bug_account_without_repos

DataManager: return empty list when account has no repos
Merge pull request #87 from alfh/bug_exception_upload_image

BrowserActivity: handle case where no path is returned for file to upload
Merge pull request #88 from alfh/bug_clean_recent_and_watched_files

SeafileObserver: Remove files from watched and recent lists
fix some bug and remove withToken param of SeafConnection.prepareApiDeleteRequest
Merge pull request #84 from asv000/master

Implemented file/folder delete operation
fixed project.properties and indention
fixed indetion