Update OpenShift Docs for Ruby 2.0 Cartridge

Update the instructions for OpenShift for the newly added Ruby 2.0
Cartridge. Due to an older version of Bundler, some workarounds have
to be included.
Set SECRET_TOKEN as OpenShift Environment Variable

This sets the SECRET_TOKEN variable as OpenShift Environment Variable,
rather than committing the SECRET_TOKEN to the repo.

[skip ci]
Merge pull request #342 from jasonngpt/updateOpenShiftDocs

Update OpenShift Docs for Ruby 2.0 Cartridge