Support for Red Hat based systems when /etc/issue does not contain distro information
Add a helper to run commands with fallbacks
Default to `lsb_release` for detecting the Linux distro

/etc/issues is very unreliable as it is often modified by providers.
Merge pull request #242 from tmatilai/prefer-lsb_release

Default to `lsb_release` for detecting the Linux distro and add support
for RHEL based systems where /etc/issue is modified.

Fixes #234 too.