first stab at supporting database 'url' for connection

tests to come
fix CS
fix wrong variable use in parse_url
fix return values
fix undefined $url
some tests for database URLs
fallthrough scheme tests, and turns out underscores are a no go :(
support dashes in schemes for db drivers, translated to underscores
remove underscore from method name as per feedback
remove underscore from member name as per feedback
erp, typo, wat
early assign as per feedback
fix backslash prefix
remove redundant check as per feedback
docs :)
Merge branch 'master' into database_url
Merge pull request #729 from dzuelke/database_url

Support for database URLs