Reorganize dependency errors section of README

This change moves the Example Dependency Errors section above the
section Fixing Dependency Errors so that the reader finds the more
common errors with their exact fixes before the list of the more
generalized error fixes.

Other changes include:

- Add reference links between the two re-organized sections to
  facilitate troubleshooting.
- Add notes regarding the use of the `grunt bower:update` command
  as well as when it should be run.
- Make section heading text match style of related sections by
  using appropriate capitalization as well as revising their length to
  have fewer words.
- Fix minor typo