- Do not get the video mimeType from MimeTypeMap if it was already set in the cursor.
- When both cursor and MimeTypeMap fail to retrieve the mimeType, try to guess it by using URLConnection.
- When all of the previous method fail, set an empty mimeType.
Moved the code that retrieves the mimeType of a Media File to a utility method.

We can't live without mimeType.
Just renamed a variable
Make sure the file has an extension, otherwise WordPress (server) can't match the mime type by using the filename provided in the request.
Split 'getMediaFilenameAndMimeType' in 2 different functions.
Fix an issue where 'getMediaFileMimeType(File mediaFile, boolean isImage)' is called with false on images
Merge pull request #941 from wordpress-mobile/issue/926-NPE-video-mimeType

NPE - video mime type