Travis: Don't run offlineTests as part of integrationTests also

Because integrationTests pulled in offlineTests, the overall build
took too long.
Travis: reduce Xmx to 1G from 2G so we can do more processes

With sbt server we may have a fair number of JVMs so we need to
avoid immediately consuming the entire 3G on Travis.
Merge branch 'wip/havocp-from-1.2.x' into wip/havocp-merge-master