Allow empty string for optionValuePath on fm-select

[g-cassie]

This change makes it possible to set optionValuePath='' and have the entire object from the content list be set to the value of the property. This is a very common pattern with Ember-Data.

This behaviour was working prior to 8feb869 when we switched over to the built in get helper. This restores the previous functionality and adds a test.

[g-cassie]

These failures seem to also exist on master... I think there is something going on with Ember-Try. I noticed on @jelhan 's PRs that the builds were failing on beta - maybe this is biting us now?

Edit: @Emerson I think you have may broken some of @jelhan 's tests when you added the fm-config.showErrorsByDefault property.

[jelhan]

@g-cassie Tests are fixed in #45. Especially 8b1aef4 should be necessary to get the tests running.

[Emerson]

So nice to see the green "Passing" text again – thanks @g-cassie

[g-cassie]

That was mostly @jelhan on that one. @Emerson can you take a look at our discussion in #37 when you have a chance? I think I will start out on that later today.