Make a separate travis job for android

Since the download and install of the android sdk sometimes takes very
long time, build and deploy android in a separate travis job. The
environment variable ANDROID=true is only used to be able to distinguish
the two oraclejdk7 jobs in the travis build matrix.
Merge branch 'travis-android-separate' of https://github.com/brasmusson/cucumber-jvm
Attribution. Closes #581, #584