2.4.0

• Update gradle 3.3 -> 4.1
• Update gradle-release-plugin 2.5.0 -> 2.6.0
• Update gradle-quality-plugin 2.1.0 -> 2.3.0
• Update gradle-animalsniffer-plugin 1.2.0 -> 1.4.1
• Update gradle-versions-plugin 0.13.0 -> 0.15.0
• Update gradle-java-lib-plugin 1.0.4 -> 1.0.5
• Update coveralls-gradle-plugin 2.7.1 -> 2.8.1
• Update spock to 1.0 -> 1.1
• Update travis config:
  • increase check task timeout to 20 min
  • disable gradle daemon (recommended)
  • remove TERM=dump (set automatically by travis)
  • update cache management