Fix pypi element README.md errors

- pip install to a github URL without a git+ prefix fails.
- Need to close EOF heredoc when creating mirror.yaml

Change-Id: Ic555174881e9c06fede1cf731141cbe6eb0e0b02
dkms is unavailable on RHEL and derivatives

The dynamic kernel module system is not available on RHEL, CentOS,
Scientific Linux, or SUSE.  Make it part of the distro post-install
rather then base post-install.

Change-Id: Ic2c345bf9f0738dadae611194e263d3a5d424a3e