When uunmarshalling uuid's, check if data is empty

If data is empty then it should be treated as null.
Merge pull request #100 from Zariel/fix-unmarshal-null-uuid

When uunmarshalling uuid's, check if data is empty
added password authentication support for Cassandra 2
Merge branch 'master' of https://github.com/tux21b/gocql
prepare all DML queries
Update readme urls
Fix duplicate protocol
Merge pull request #103 from Zariel/update-readme

Update readme urls
increase default connection timeout significantly
also increase the timeout in the testcase