Server info

Adding more supported XEPs to the list on the account details screen was discussed in #574. It was decided that a show more button would reduce clutter, but still allow people to get info about their server. Unfortunately, I forgot about it (and did something weird when rebasing from the looks of the issue) until just now.

If this is still of interest, I added a show more button, and added MaM and Blocking to the list (in the regular list and the show more list respectively).

I'm not sure that the button looks great; maybe a link would be better.

![screenshot_2014-12-22-14-46-50](https://cloud.githubusercontent.com/assets/512573/5530108/38501da0-89ea-11e4-828c-b684890cff30.png)
![screenshot_2014-12-22-14-46-45](https://cloud.githubusercontent.com/assets/512573/5530109/38524710-89ea-11e4-997e-98edd80de5cb.png)

(MAM string is different from the screenshots; it now reeds `MAM (History)`; a cue I took from `PEP (Avatars)`.