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.
This section should not be here, full stop. This is specific to Git sources, and I fully intend to add more source specific options as time progresses. This is in the **Source Options** section of configuration (https://github.com/rnelson0/r10k/blob/gh-120-workflow-documentation/doc/dynamic-environments/configuration.mkd#source-options) which explicitly notes that "Sources may implement other options in addition to the ones listed below; see the source specific documentation for more information." I will not merge this pull request with this change.