Add support for Options (Some/None) in prepared stmt parameters

Allows to specify Some(value) or None in prepared stmt parameters,
as until now an Option had to be passed as opt.getOrElse(null).

Is implemented for mysql and postgresql.

Closes #30
Support 'postgres' protocol in heroku like db urls.

Heroku like db urls were supported with 'postgresql' protocol.
In my heroku app, the DATABASE_URL was set with 'postgres' protocol,
so that the db url could not be parsed.

This change supports both 'postgresql' and 'postgres' protocols.
Merge pull request #33 from magro/support-postgres-protocol

Support 'postgres' protocol in heroku like db urls.
Merge pull request #31 from magro/support-options

Add support for Options (Some/None) in prepared stmt parameters
Support db urls without port and username/password.

The database url had to include port, username and password, like this:
`jdbc:postgresql://localhost:5432/mydb?username=foo&password=bar`

This change allows to leave out port or username/password, like this:
`jdbc:postgresql://localhost/mydb`
(for simplicity only both username and password can be left out, not
username or password)

This is implemented for `jdbc:postgresql` protocol, not for heroku
`postgresql`/`postgres` protocol.

This commit also includes a change of the default port from 5234 to 5432.

Closes #32
Simplify ParserURL.parse, check different regexps in single match clause
Merge pull request #34 from magro/fix-db-url-parser

Support db urls without port and username/password
Fix jdbc:postgresql url format to use 'user' instead 'username'.

When using a jdbc:postgresql url valid according to the current ParserURL
the jdbc driver (used by the evolutions plugin) cannot connect to the db
as it's missing the user connection parameter.

According to the postgresql jdbc driver documentation the correct parameter
is 'user' instead of the previously used 'username' - this shouldn't have worked
for anyone.
See: http://jdbc.postgresql.org/documentation/91/connect.html#connection-parameters
Change README to mention 'user' instead of 'username.
Merge pull request #35 from magro/fix-jdbc-postgresql-url-format

Fix jdbc:postgresql url format to use 'user' instead 'username'.
Reuse the same NioClientSocketChannelFactory for all connections - fixes #36
Fixing failed build and updating dependencies
Closing 0.2.4
Preparing for next version
Update CHANGELOG.md
Fixes #38 - also requires providers to implement an NioClientSocketChannelFactory
Fixing the scala version
Updating scala version on travis
Adding a query with limits
Updating changelog and readme