Add android.ant_path to default.spec

[akkana]

I have kivy and ant installed from debian packages, buildozer from git because there is no debian package. Following a tutorial, I ran
buildozer android debug deploy run
and noticed it wanted to download a new version of ant:
Android ANT is missing, downloading

Poking through the source of buildozer I discovered that it checks a config variable android.ant_path, but that variable wasn't in the buildozer.spec file it created for me. Since android.ndk_path and android.sdk_path were in the default spec, it would have been helpful if android.ant_path was too.

[dvenkatsagar]

👍 +1