[skip CI]

Update ReadMe with typo fix

Test ruby 2.2 in travis

test-unit was removed from ruby 2.2's standard library

Rails 3.2.22 adds support for ruby 2.2
http://weblog.rubyonrails.org/2015/6/16/Rails-3-2-22-4-1-11-and-4-2-2-have-been-released-and-more/

sqlite3 1.3.7 does not work with ruby 2.2.2
https://gist.github.com/zzak/695d1e25ec13d62ca671#gistcomment-1364746

Enforce initial password format

This behaviour should be sufficient for the vast majority of
applications, but has also been extracted into a new method so that it
can be overridden if necessary.

If `Devise.friendly_token` happens to return a string that does not
contain an upper case char / lower case char / digit / symbol, then this
can cause (in some applications) the invited user to be invalid!

Change :allow_insecure_sign_in_after_accept documentation

Changing the default value breaks a *lot* of tests. Change the documentation instead.

Comments say `default: false` but default value was `true` :-/

Update versions in example Gemfile

Update example Gemfile with latest versions of devise-invitable and devise

Don't override password

Fix links

Set random initial password for invited users

Update CHANGELOG as of 2015-06-22

A lot of these bullet points could be paraphrased (better), but
this is at least a starting point.

[ci skip]

Add support for setting invited_by foreign key