Update to `npm install` command

fixes #1053

- npm install doesn't need a path to grunt, and fails on Windows if it has one
- submodule update is handled by grunt (albeit badly... but let's fix that!)
Merge pull request #2176 from ErisDS/issue-1053

Update to `npm install` command
Helper updates for Tag Pages

fixes #2112
refs #1833

- modified config.urlFor to handle tag pages

- modified {{#tags}} handlebars helper to autolink to
  tag pages. Additional autolink="false" parameter can
  be used to deactivate autolinking

- modified url handlebars helper to handle tags

- added isTag function to schema

- added unit test for additional urlFor functionality

- added unit test for {{#tags}} helper modifications

- added unit test for url handlebards helper