First draft of README.markdown.

Switching to a new format as documented here:
https://docs.puppetlabs.com/puppet/3/reference/modules_documentation.html
Second pass at README.markdown updates.
Removed all template notes from README.markdown.
Added Cloudera Certified logo to README.markdown.
Third pass at README.markdown updates.
Renamed yumserver and yumpath parameters to repo*.

Added sections to the table of contents.
Added license in README.
Changed name of module in README from 'cloudera' to 'Cloudera Manager'/
Added deprecation warning for yumserver and yumpath.