Change Where am I to Where is this on left sidebar

Related to #373

"Where am I?" is short for "Where am I looking at?" but prone to be interpreted as "Where am I located right now?"

This pull request changes it to "Where is this?" I considered "Where am I looking at?" but the at? is pushed onto the next line, consuming vertical sidebar space.

It does not make the side text any longer and should be a clearer description of what the feature does.

Current:
![where_am_i](https://f.cloud.github.com/assets/1190866/909150/367a532e-fdb4-11e2-8bf0-0a95db7f03b1.png)

Where am I looking at?:
![where_am_i_looking_at](https://f.cloud.github.com/assets/1190866/909151/3680fe04-fdb4-11e2-942e-08dbcea0cb1e.png)

Where is this?:
![where_is_this](https://f.cloud.github.com/assets/1190866/909152/3683544c-fdb4-11e2-83a3-e5825f38df19.png)