[java travis] Pull down git tags before starting the build
[java travis] Pull down git tags before starting the build

Without this, Java may automatically configure a version string equal to
the checked-out hash prefix, which has a 6/16 chance of starting with a
letter instead of a number. Gradle doesn't seem to resolve dependencies
properly when this happens.

We need the full history so that we have an unbroken chain from the
current commit to the most recent tag.

Fixes https://github.com/Microsoft/bond/issues/835
chwarr/bond,chwarr/bond,jdubrule/bond,Microsoft/bond,chwarr/bond,jdubrule/bond,jdubrule/bond,chwarr/bond,Microsoft/bond,Microsoft/bond,jdubrule/bond,Microsoft/bond,jdubrule/bond,chwarr/bond,Microsoft/bond,chwarr/bond,Microsoft/bond,jdubrule/bond