Just a little fix on the login spinner in chapter 17

[rmnblm]

I was reading the book and studied the code and found a little mistake.
Not going to make a pull request because of this.

https://github.com/scotch-io/mean-machine-code/blob/master/17-user-crm/public/app/views/pages/login.html#L31

Just replace
<span ng-if="login.processing" class="spinner"><span class="glyphicon glyphicon-repeat"></span></span>

with
<span ng-if="login.processing"><span class="glyphicon glyphicon-repeat spinner"></span></span>

By the way: Thanks for this awesome book!

[sychen41]

Thanks