Added description support for migrations

Signed-off-by: Michał Zalewski <michal@mzalewski.net>
Merged with upstream/master
Added IVersionMetaDataEx(tended) closes  #295
Choose the least breaking way of implementing this feature
Renamed IVersionTableMetaDataEx to IVersionTableMetaDataExtended, just to reveal intend better
Partially reverted ForwardOnlyMigration closes #436
Merge branch 'master' of https://github.com/drucik86/fluentmigrator into drucik86-master
Fix issue with versionloader and fix tests
Merge pull request #401 of drucik86/master

# By Michał Zalewski (1) and Tom Marien (1)
# Via Tom Marien (2) and Michał Zalewski (1)
* drucik86-master:
  Fix issue with versionloader and fix tests
  Added description support for migrations
VersionLoader gets version column by name closes #456
Merge branch 'Issue295' of https://github.com/tommarien/fluentmigrator into tommarien-Issue295

Conflicts:
	src/FluentMigrator.Runner/VersionLoader.cs
	src/FluentMigrator.Tests/Unit/TestVersionTableMetaData.cs
	src/FluentMigrator/VersionTableInfo/DefaultVersionTableMetaData.cs
Merge pull Request #427 of tommarien/Issue295

* tommarien-Issue295:
  Renamed IVersionTableMetaDataEx to IVersionTableMetaDataExtended, just to reveal intend better
  Added IVersionMetaDataEx(tended) closes  #295 Choose the least breaking way of implementing this feature
Bumped version to prepare for release
Fallback to Migration Type name if Description is not supplied closes #458
Fixed description column to string(1024) as int.MaxValue was not supported yet for every processor
Merge branch 'FB-457' of https://github.com/tommarien/fluentmigrator into tommarien-FB-457
Merge pull request #460 of tommarien/FB-457

* tommarien-FB-457:
  Fallback to Migration Type name if Description is not supplied closes #458
Bumped version for patch release
Merge branch 'master' into GuiRunner