Rename the method so that it won't conflict with Model.checkAccess

See https://github.com/strongloop/loopback/issues/239
Remove intermediate section headers from nav
Fix constructor JSDoc
Merge pull request #242 from strongloop/feature/fix-issue-239

Rename the method so that it won't conflict with Model.checkAccess
Bump version
Merge branch 'release/1.8.1' into production
Merge tag 'v1.8.1'

1.8.1
Add CLA
Convert principalId to String
Update README and license link
Add more check on principalId
typo
Merge pull request #246 from haio/master

Convert principalId to String
Ensure roleId and principalId to be string in Role#isInRole
Merge pull request #247 from haio/master

Ensure roleId and principalId to be string in Role#isInRole
Fix client-server example
Fix bug in User#resetPassword
Add homepage to package.json
Merge pull request #252 from haio/master

Fix bug in User#resetPassword
Move content from wiki on LB modules.