[TC-2451] Fix FS on iOS 7

By relaxing the file://localhost/ prefix check to just file://, we can fix the bug preventing iOS 7 from reading and writing to the filesystem.

Works on my iPhone 5 running iOS 7, and in simulator running iOS 6.
Merge pull request #4393 from dawsontoth/TC-2451_ios7FS

[TC-2451] Fix FS on iOS 7