Move oxm and vorbis depackers to depacker directory

Signed-off-by: Claudio Matsuoka <cmatsuoka@gmail.com>
Also run the distribution package test in travis-ci

Signed-off-by: Claudio Matsuoka <cmatsuoka@gmail.com>
Add targets to run devcheck and covercheck

Regression tests are not in the distribution package anymore, but keep
these targets so we can run them easily.

Signed-off-by: Claudio Matsuoka <cmatsuoka@gmail.com>
Update changelog

Signed-off-by: Claudio Matsuoka <cmatsuoka@gmail.com>
Test travis build script

Signed-off-by: Claudio Matsuoka <cmatsuoka@gmail.com>