Added RecyclerView to build.gradle
Reduced number of jobs to one

This avoids memory spikes when more than one image is decrypted at the
same time.
Fixed NPE when deleting file without thumbnail
Fixed NPE when loading file with missing header
Removed onCreate from FileViewer

onCreate seems to be never called. It further would not work anymore
because opening a file without a loaded vault would not work.
Changed list_file layout to RecyclerView
Unregister VaultListFragment from EventBus when destroyed
Changed FileList to Recyclerview
Merge pull request #57 from L-Henke/recyclerview

RecyclerView
Added missing DecryptingFileDoneEvent
Merge pull request #59 from L-Henke/recyclerview

Added missing DecryptingFileDoneEvent
Getting ready for 5.0 release
Improved image scaling

Images are now scaled directly at creation. This allows to load even
large images without out of memory problems.

It further allows to set the max scaling factor according to device
limitations.

Since the inSampleSize scaler can only scale to factors of 2, the
resulting image size is somewhere between MAX_PIXEL/2 and MAX_PIXEL.
Merge pull request #60 from L-Henke/directImageScale

Improved image scaling
Prevention of FilesActivity being killed by reading whether this is a configuration change.

Downside:
May not get the correct value and the expected behaviour may not exist in pre API-11 devices.

But those market shares...
Merge pull request #61 from Doplgangr/ui

Ui