Added possibility to use different database (storage) backends. Currently
supported: flatfiles and mysql. Fixes#2.
Added database shutdown call. This call will properly shutdown database
connections (in case of RDBMS) or flush pastes index cache on disk (in
case of flatfiles).
De-hardcoded pagination count. Fixes#12.
Pagination now works. Temporary hardcoded 10 pastes per page, will be put
in configuration later. Maybe.
From now user will receive readable error message if error occured.
Started to work on syntax highlighting, tried to make lexers detection
work but apparently to no avail.
