Fix </i> tag from icons being visible in board dropdown

This fixes the issue where HTML was sometimes visible in the discussion xblock's board dropdown menu:

![screen shot 2014-09-17 at 12 34 32 pm](https://cloud.githubusercontent.com/assets/945577/4309953/d646897a-3ea1-11e4-9727-f0b795144329.png)

### Fix: ###
* Use `.text()` instead of `.html()` to strip out the `<i></i>` icon tags (Note: this only works if the tags precede the text, although that is the case, but that is how all the menus are coded)
* Fixed a logic error in the `DiscussionThreadListView.fitName()` method that would prepend `…/` to the name even for board names with no parent (see screenshot below).

![screen shot 2014-09-17 at 12 21 02 pm](https://cloud.githubusercontent.com/assets/945577/4310024/783a8948-3ea2-11e4-8983-fa0dec2e094f.png)


### Result: ###
Fixed in client frontend:
![screen shot 2014-09-17 at 12 26 59 pm](https://cloud.githubusercontent.com/assets/945577/4310034/88d42462-3ea2-11e4-848a-00f6efe1f54e.png)

and tested working in solutions LMS:
![screen shot 2014-09-17 at 12 29 00 pm](https://cloud.githubusercontent.com/assets/945577/4310046/a3569518-3ea2-11e4-9bb2-b268568abbc4.png)

### Known issue: ###
There is a remaining minor issue that could be addressed in future if anyone deems it important. The `fitName()` method has some design-related values that are hard-coded with no explanation:
![screen shot 2014-09-17 at 12 27 22 pm](https://cloud.githubusercontent.com/assets/945577/4310071/f383ab02-3ea2-11e4-83a4-21ca3f054733.png)

Unfortunately the values seem no longer correct, at least in my browser, resulting in inconsistent displays:

1. On the client frontend, the HTML does not match the display, as the text is one character too wide:
![screen shot 2014-09-17 at 12 26 34 pm](https://cloud.githubusercontent.com/assets/945577/4310125/8622257e-3ea3-11e4-8dd7-0cdb16a20a3f.png)
Appearance is seen above, but the HTML used is:
![screen shot 2014-09-17 at 12 26 50 pm](https://cloud.githubusercontent.com/assets/945577/4310128/893cedd4-3ea3-11e4-83b8-5447c27e2da3.png)


2. On the solutions LMS the arrow changes visibility when resizing the browser window:
<table><tr><td>
<img src="https://cloud.githubusercontent.com/assets/945577/4310083/1cc60230-3ea3-11e4-959f-0cba4c2b51ad.png">
</td><td>vs</td><td>
<img src="https://cloud.githubusercontent.com/assets/945577/4310087/2a45d0f2-3ea3-11e4-9c07-3884ad65b2b3.png">
</td></tr></table>