[RFR] Add Theming support

[fzaninotto]

• Add support for custom CSS classes in the datagrid columns

myEntity.listView()
    .addField(new Field('title').cssClasses(['foo', 'bar']));

• Add support for custom CSS class functions everywhere

myEntity.editionView()
    .addField(new Field('title').cssClasses(function(entry) {
        return entry.values.needsAttention ? 'bg-warning' : '';
    }));

• Add ability to customize template for each view

var myEntity = new Entity('foo_endpoint');
// customize list view template
myEntity.listView().template(require('text!./path/to/list.html'));
// continue myEntity configuration
// ...
app.addEntity(myEntity);

• Add ability to customize template for each view for the entire application

var myTemplate = require('text!./path/to/list.html');
app.customTemplate(function(viewName) {
    if (viewName === 'ListView') {
        return myTemplate;
    }
})

• Add Theming documentation

Closes #138, #118, #110.

[fzaninotto]

Switching to RFR, will merge shortly if no feedback.

[manuquentin]

👍 nice work! Good for me

[cmnstmntmn]

i have

    var listView = require('./custom-views/listView.html');

    admin.customTemplate(function (viewName) {
        if (viewName === 'ListView') {
            return listView;
        }            
    });

and inside it <div ui-view="grid"> </div>

the problem is, that javascript/ng-admin/Crud/list/list.html cannot be overwriten;
it contains extra markup, not only directives.

<div class="row list-view" ng-class="::'ng-admin-entity-' + listController.entity.name()">
    <div class="col-lg-12">
        <ma-datagrid name="{{ ::listController.view.name() }}"
                  entries="listController.dataStore.getEntries(listController.entity.uniqueId)"
                  selection="selection"
                  fields="::listController.fields"
                  list-actions="::listController.listActions"
                  entity="::listController.entity"
                  datastore="listController.dataStore">
        </ma-datagrid>
    </div>
</div>

<div class="row" ng-if="::!listController.infinitePagination">
    <div class="col-lg-12">
        <ma-datagrid-pagination
            page="{{ listController.page }}"
            per-page="{{ ::listController.view.perPage() }}"
            total-items="{{ listController.totalItems }}"
            set-page="::listController.setPageCallback">
        </ma-datagrid-pagination>
    </div>
</div>

<ma-datagrid-infinite-pagination ng-if="::listController.infinitePagination"
            per-page="{{ ::listController.view.perPage() }}"
            total-items="{{ ::listController.totalItems }}"
            next-page="::listController.nextPageCallback">
</ma-datagrid-infinite-pagination>