Add python-sip to ubuntu-precise; resolves travis-ci/apt-package-whitelist#2015
Add python-sip to ubuntu-precise; resolves travis-ci/apt-package-whitelist#2015

Packages: python-sip python-sip-dbg python-sip-dev sip-dev sip-dbg python-sip-doc python3-sip python3-sip-dev python3-sip-dbg

travis-ci/apt-package-whitelist,travis-ci/apt-package-whitelist