Use .crm-container instead of #crm-container when possible

Because popups, blocks, and some snippets are outside the #crm-container div they do not get any of our css applied to it.

Proposed solution:
-On the main civicrm template that generates the crm-container div, add the class crm-container (without removing the id)
-In civicrm.css, change some instances of #crm-container to div.crm-container as necessary

Because we don't remove the id #crm-container from our markup, anyone who targets it in their custom css files will not be affected.

Note: css selectors containing ids always trump those which do not, so we need to be careful when changing our css - removing the id from the selector may cause some CMS styles to override ours. For now we'll only change those which are actually needed for specific popups. If necessary we can use the following verbose but effective pattern in our stylesheet to cover both the main div and other crm-containers:

#crm-container .messages,
.crm-container .messages