fix EnumToString conversions for Enums implemented in Groovy
fix querying collections by single element
for example MyCollections.findByNames("Bob")
Improve GString (CharSequence) support in conversions
Fix failing test InheritanceSpec that failed because BigDecimal was stored as Integer.
- only store Integer and Short instances as Integer
Merge pull request #131 from lhotari/master

Fix failing tests in grails-datastore-gorm-mongo because of ConversionService changes