Merge pull request #14 from vizcay/master

improve FbColumn#initialize so that limit, precision & scale get set only for correct column types
Set limit for CHAR types, but no longer needed for BLOBs.
Bump version to 0.8.1.
Fix "singleton can't be dumped" marshaling error.
Bump version to 0.8.2.
Add columns method to FbArray
Merge pull request #15 from rzane/master

Add columns method to FbArray for select_all - Rails 4
fixed #change_column, add_column_options raising 'undefined method'