Faster and more reliable build

[gustavoamigo]

• Migrated Docker image to Alpine for faster builds
• Verifies if databases are ready before running script

[gustavoamigo]

Really weird, I got this error.

06:26:38.358 [pool-1-thread-1-ScalaTest-running-JdbcEncodingSpec] INFO  i.g.s.jdbc.mysql.package$$anon$1 - SELECT t.v1, t.v2, t.v3, t.v4, t.v5, t.v6, t.v7, t.v8, t.v9, t.v10, t.v11, t.o1, t.o2, t.o3, t.o4, t.o5, t.o6, t.o7, t.o8, t.o9, t.o10, t.o11 FROM EncodingTestEntity t WHERE t.v6 IN (?, ?)
[info]   - long *** FAILED ***0m
[info]     List() did not contain the same elements as List(1, 0) (MysqlAsyncEncodingSpec.scala:39)

[fwbrasil]

@gustavoamigo thanks for working on this! It's much appreciated. :)

I think there's a concurrency issue in MysqlAsyncEncodingSpec.scala, the calls to prepareEncodingTestEntity outside an in clause don't guarantee ordering.

[gustavoamigo]

@fwbrasil All right, at least the docker-compose run setup step went down to 55s from previous 112.81s.

[fwbrasil]

Awesome! From ~12m to ~9m! 👍

[fwbrasil]

I'm going to fix the flaky test.