- activate travis build

Hy,

to prepare the multidbcake example that i want to push (https://github.com/nafg/slick-migration-api/issues/1). I activate travis build and coveralls coverage report for the project.

On travis there also the mysql and postgres test are succesfully performed take me a while to get it work but here it is.
I start use your migration api in my https://github.com/pussinboots/unitcover project and it saves me a lot of time to think about how i can perform database migration for the heroku production version.

So thanks for the simple to use migration api
great work
I've found out there is a problem when the MySQLTest and PostgresTest are
performed in parallel. That' not happen very often on my local machine because sbt
start only 2 Tests parallel (depends on available cpu's i guess). But Travis has a lot of available cpu's. Look Here it starts all test parallel and got freezed

[debug] Running TaskDef(scala.slick.migration.api.HsqldbTest, org.scalatest.tools.Framework$$anon$1@16fadd5c, false, [SuiteSelector])
[debug] Running TaskDef(scala.slick.migration.api.PostgresTest, org.scalatest.tools.Framework$$anon$1@16fadd5c, false, [SuiteSelector])
[debug] Running TaskDef(scala.slick.migration.api.SqliteTest, org.scalatest.tools.Framework$$anon$1@16fadd5c, false, [SuiteSelector])
[debug] Running TaskDef(scala.slick.migration.api.MigrationSeqTest, org.scalatest.tools.Framework$$anon$1@16fadd5c, false, [SuiteSelector])
[debug] Running TaskDef(scala.slick.migration.api.H2Test, org.scalatest.tools.Framework$$anon$1@16fadd5c, false, [SuiteSelector])
[debug] Running TaskDef(scala.slick.migration.api.MySQLTest, org.scalatest.tools.Framework$$anon$1@16fadd5c, false, [SuiteSelector])
[debug] Running TaskDef(scala.slick.migration.api.DerbyTest, org.scalatest.tools.Framework$$anon$1@16fadd5c, false, [SuiteSelector])