LinkedIn API: Display education only if user listed that on their linkedin profile.

Fixes #138
Check if email is already taken when creating a new local account
Updated sign-in strategies.

Removed email check when trying to link multipel accounts. Otherwise trying to link facebook and google that use the same e-mail is impossible.
Updated sign-in strategies in generator.js
Updated README changelog and version number
Merge remote-tracking branch 'origin/master'