Merged Gemfile from ruby200 to master by mistake, thus rollback Gemfile on master branch

Change-Id: Ie0d764c345369b268488dd4ae766ca4c1124e53f
Merge branch 'ruby200'

Conflicts:
	Gemfile

Change-Id: I6ddd5d60aba2b80dfdb67ea3d8bc61318b7927ab
Merge branch 'ruby200'

Conflicts:
	Gemfile
Fix an error in Gemfile while merge conflicts
Merge branch 'ruby200'
Merge branch 'ruby200'
Merge branch 'ruby200'

Conflicts:
	Gemfile.lock

Change-Id: Iab67e827ce949ccc06561bfe6e06913011f2c200
Exercise 9.6.1: Add a test case by issuing a PATCH request directly to /users/17?admin=1, verify that the admin attribute isn’t editable through the web
Exercise 9.6.2: Arrange for the Gravatar “change” lin3 to open in a new window (or tab)
Exercise 9.6.3: Add tests to make sure that links such as 'Profile' or 'Settings' don’t appear when a user isn’t signed in
Exercise 9.6.4: Use the sign_in test helper in as many places as you can find
Exercise 9.6.5: Remove the duplicated form code by refactoring the new.html.erb and edit.html.erb views to use partial _fields.html.erb

Note you will have to pass the form variable f explicitly as a local variable ('<%= render 'fields', f: f %>')
Exercise 9.6.6: Signed-in users have no reason to access the new and create actions in the Users controller. Arrange for such users to be redirected to the root URL if they do try to hit those pages.

Change-Id: Ibdab3271a73af9d6f8e757373ff060d0af26883a
Exercise 9.6.7: Learn about the request object by inserting some of the methods listed in the Rails API into the site layout

Change-Id: I3e878d56e94241cf3d2e6ff62e32bf1ef636ed1e
Exercise 9.6.8: Write a test to make sure that the friendly forwarding only forwards to the given URL the first time. On subsequent signin attempts, the forwarding URL should revert to the default.

Change-Id: Id63e696da832f117f681adc54f9a9695a1a6921a
Exercise 9.6.9: Modify the destroy action to prevent admin users from destroying themselves

Change-Id: I5556c7273ff9946ed0c6263e37f0140a0a45de9a
Revert Gemfile to linux version (was overwritten by merging from 'master', which is a windows branch)