NPE fixes, triggered by empty database
NPE fix. unknown to reproduce (31c3 play store report)
Proguard: Don't obfuscate, only optimize
Version 1.30.4
Update Gradle wrapper version
Make Gradle wrapper executable
Remove 30c3 flavor
Merge pull request #76 from cketti/31c3_only

Remove 30C3 Gradle flavor
Add configuration for Travis-CI.

+ Add signing configurations for ccc31c3 flavor
  to gradle.properties.