Making frequency of version update checker (CHECKVERSION) configurable

Adds an option in Config > General > Misc called "Update Frequency"

Closes #54
Making frequency of version update checker (CHECKVERSION) configurable

Conflicts:
	sickbeard/__init__.py
Fix for backlog searches
Merge branch 'pulls/95'
Disabled sceneConvert renamer for now till we add it in optionally.
Fixes issue with update frequency.
Fixes backlog search issues with newznab providers.
Fix for update frequency ... again!
Added in min_update_frequency
Fix for new shows
Centering the header, by popular demand
Fix for sql mass add issues.
Fix for KAT and TPB providers.
Fix for Newznab providers.
Fix for air-by-date and sports shows
Fixes interval setting for auto updates and check version, will set the interval in realtime and take effect right away.
Fixed missing UPDATE_FREQUENCY from globals.
Merge pull request #118 from WebSpider/center_header

Centering the header, by popular demand
Fix for adding and importing shows
Fix for FINDPROPERS
Fix for mediabrowser absolute_number issue
Fix for subtitles datetime issue
Code cleanup.
Fix for exception error in TorrentLeech