Address the concerns of #345

This adds the ability for a user to set their own html resources,
intended for use by developers when debugging compatibility issues.

The API for this is as follows:

* The mine admin must enable this feature by setting
"head.allow.user.overrides = true" in any property file that
contributes to `WEB_PROPERTIES`.
* The user should then identify the key of the property they wish to
override. This is easily done by inspecting the head where each resource
has a comment indicating its key.
* The user should indicate their preferred value by running the
following js in the console:

```:js
$SERVICE.whoami().then(function(user) { user.setPreference(key, value)});
```

eg. to replace bootstrap with a different version, the user would run:

```:js
$SERVICE.whoami().then(function(user) {
    user.setPreference(
        'head.js.all.Ac',
        'http://cdn.intermine.org/js/backbone.js/0.9.9/backbone-min.js'
    );
});
```
closes #350
Merge branch 'intermine-1.2.1' of github.com:intermine/intermine into intermine-1.2.1
Fixes #334

_.partial was new in underscore@1.4.4
Some documentation fixes
Fixes #352
Updated css version
closes #363
Merge branch 'intermine-1.2.1' of github.com:intermine/intermine into intermine-1.2.1
closes #356
closes #357
Refactored the bag status queries, and added a general method.
Don't upgrade if already upgrading
Whoops - forgot a bang
Don't wait for upgrades in webservice requests. It is stupid
added config to merge web-model.xml and web.xml #313 #309
Merge branch 'intermine-1.2.1' of github.com:intermine/intermine into intermine-1.2.1
merge web-bio.xml and web.xml #313 #309
a fix to #351
Fix widget inheritance. From @sneuhaus Closes #368