Avoid dynamic connection of 'recorder-error' signal in recorderui.

The signals are managed by the galicaster dispatcher service, and a dynamic connection/disconnection is not necessary.
Delete signal 'update-rec-status' (clean code)
Rename signal "update-rec-vumeter" to "recorder-vumeter".

Using the same prefix in all the recorder signals. ("recorder-vumeter", "recorder-error"...)
Add test for galicaster.recorder.recorder
check valid number of bins in recorder constructor
Fix UnboundLocalError: local variable 'mod_name' referenced before assignment
Style changes in recorder
Add recorder get_bins_info and get_display_areas_info test
Style changes. Separate top-level function and class definitions with two blank lines
All the recorder errors are managed by the 'recorder-error' signal handler
reorder recorder functions
Add recorder preview test
Fix recorder after executing pyflakes
New not async recorder
New not async recorder test