Merge pull request #138 from dekpient/master

Fix on stage visual discrepancies and player info validation
Fix deleting media error
changed issue #94

Search by string now ignores case and searches both name and stream name
fixed issue #130

When the medium filter isn't applicable it will be empty.
Fixed Issue #125
Add another empty slider for selecting audio time
Save audio duration on server using PyMad
Use DejaVu font to support unicode symbols
Client stores audio duration
Support custom start/stop position for audios (server-side)
Overhaul AudioSlot and support start/stop position