base: DocumentUI: fix a few issues handling remote content

http://jira.omnirom.org/browse/OMNI-956
http://jira.omnirom.org/browse/OMNI-950

Change-Id: I8d50d71a9c91486dfc9e5da01538c6b5a626f054

Conflicts:
	packages/DocumentsUI/src/com/android/documentsui/DirectoryFragment.java
	packages/DocumentsUI/src/com/android/documentsui/DocumentsActivity.java