Add speaker class to each speaker

Add speaker class to all speakers so that you can style them. I only did the first few people but you should do all of the speakers this way.  Then you will be able to change the layout with one selector in your sass like: 
````
@include breakpoint(medium){
    .speaker{
       @include col(1,2);
    }
}

@include breakpoint(x-large){
    .speaker{
       @include col(1,4);
    }
}

````

Also remember that when you add spaces between works in class="" then it treats each one as a separate class so
````class="sheila solomon klass"````
will create three classes, sheila, solomon and klass. You really only need to use their last names. It doesn't hurt anything so you can just add the speaker class for now but FYI in the future you could have just used last names like:
````class="speaker klass````

You can merge this pull request to get you started. You will still need to add speaker class to the rest of the speakers. If you like you can do edit the files right on GitHub and they will show up on the github.io pages.