Added functionality to use CLoader / CDumper from yaml

This takes advantage of a c-library (libyaml) if its available for faster loads and saves.

For ProjectInfo's that are from F@H data you have large files (several MB) which may not seem very big, but loading a file can be a pain:

```
vspm24:f14g schwancr$ cat load.py
from msmbuilder import Project
p = Project.load_from('ProjectInfo.yaml')

vspm24:f14g schwancr$ time python load.py 

real	2m44.604s
user	2m37.429s
sys	0m3.438s
```
But if you use libyaml:
```
vspm24:f14g schwancr$ time python load.py 

real	0m20.194s
user	0m19.483s
sys	0m0.702s
```
Which is much more convenient in my opinion