delay connection.getMetaData esp. with queries, changes some signatures 
esp. caseConvertIdentifierForJdbc/Rails to accept a connection (see #453)
avoid connection.getMetaData on Oracle with exec_query (fixes #453)

Oracle seems to be doing some SQL on getMetaData ... this seems to improve performance singnificantly: test run times :

before: 185-190s / 180 PS
   after:  130-150s / 125 PS
MySQL does not store upper-case identifiers (for lower case it depends)
re-build jar (compiled using jruby 1.6.8 + java 6 due compatibility)