Skip tests that require Internet access by default

Ubuntu has a quality control policy that states that package tests
should be run automatically as part of a package build. However, in
order to ensure that builds and tests are reproducible from package
source code only, Internet access is disabled in our build
infrastructure.

Therefore, do not run tests that require Internet access by default.
Merge pull request #66 from basak/skip-internet-tests

Skip tests that require Internet access by default