Show toast if Google Drive login fails
Do an About.Get() request to Drive API on Auth

This is needed to make sure we can access drive API. Also fixed an issue
with the previous commit using case statements without breaks.
Fix rename behavior in GoogleDriveFileProvider.move()

When doing simple renames we shouldn't be deleting the source parent
directory from the file's parent list.
Fix MIME type detection for capitalized extensions

Closes #55
Don't crash if no Google Play Services installed

Instead show a toast / error dialog. Closes #56
Block authentication and wait for auth thread

Doesn't quite work, deadlock when app is booted without wifi but then
wifi is enabled.
Move delete/unlock waits to AsyncTask
Add a timeout to prevent infinite loop
Safely dereference context in GoogleDriveAccount.startLinkOrAuth()
Use AsyncTask to launch file chooser from VolumeListActivity
Call Account.authIfNeeded() from all async tasks
Add linking to Account.linkOrAuthIfNeeded()
Make Account.linkOrAuthIfNeeded() a member function
Unset linkInProgress after linking in GoogleDriveAccount
Refresh error dialog text in VolumeListActivity.onPrepareDialog()
Comment update in FileChooserActivity.onCreate()
Clear authInProgress in GoogleDriveAccount.unlink()
Version bump to 2.0.3