GH-120 Documentation updates

  Minor formatting changes, specifically capitalization of r10k at the start of sentences.
  README.mkd:
    Update documentation links to reflect the changes below.
  docs/common-patterns.mkd:
    New document showing common patterns to advise users.
  docs/dynamic-environments.mkd:
    Add link to workflow-guide.mkd.
  doc/dynamic-environments/configuration.mkd:
    Move invalid_branches description to this file.
  doc/dynamic-environments/git-environments.mkd:
    Comment on ability to use subversion.
    Clarify the details of 'how it works'.
  doc/dynamic-environments/introduction.mkd:
    Update introduction to reflect environmentpath beginning with puppet v3.5.
  doc/dynamic-environments/quickstart.mkd:
    Provide alternate method to access a dynamic environment.
  doc/dynamic-environments/usage.mkd:
    Clarify how forge modules are treated.
  doc/dynamic-environments/workflow-guide.mkd:
    Completed workflow guide.
R10k should only be capitalized as such when it's the first word in a sentence; the proper name is `r10k`.