Updated to 0.6.2.

Releasing 0.6.1 (candidate).

* updated CHANGELOG
* added gemspec for github
* added support for predefined format expressions [resolves:#19814]

Pushed to version 0.6.

 * fixed Rakefile glitches
 * removed whitespaces
 * removed Ruby-Sequel adapter (becomes an extra gem)
 * removed assistance gem dependency