Use TNS for connecting to the db

[jgebal]

https://stackoverflow.com/questions/19536162/how-to-connect-jdbc-to-tns-oracle

[jgebal]

We want to allow utplsql-cli to connect to DB using TNS names instaed of forcing them to provide full connect string

[viniciusam]

I expect that to be solved on the branch:
https://github.com/utPLSQL/utPLSQL-cli/tree/feature/remove_connection_parser

I changed the client to use the PoolDataSource to get the connections, and now I'm just passing the connection string without any parsing.

[pesse]

Fixed via #42