Pair messaging 1 953

Each screenshot kills two stones with 1 bird (I don't condone the killing of animals and therefore prefer to kill rocks instead). This is part of #953 
## No favorite pairs saved; default state (and error message)
![screen shot 2014-10-07 at 4 26 25 pm](https://cloud.githubusercontent.com/assets/5728307/4551952/b8b399b0-4e79-11e4-8f3c-eacb1658548a.png)

## Favorite pairs saved; Creating a new pair 
![screen shot 2014-10-07 at 4 27 29 pm](https://cloud.githubusercontent.com/assets/5728307/4551945/aadd3ce2-4e79-11e4-85d3-efc36713a3b7.png)

Parts 1 and 2 of https://github.com/stellar/stellar-client/issues/953
The important thing to realize about the change above is that the logic for deciding whether two pairs are equal should not be owned by the controller.  That logic should be delegated to something else so that others can get the same behavior without copying logic. (in this case, simply lodash to check object equality).