Extended functionality, and fixed unicode issue

Hi, 

I came across your library and it seems like a very good fit for testing some features of the product I am working on. I've extended the library, adding file and directory manipulation and some process-management functionality.

Also, we have a requirement to support VMs with unicode characters in their names, so I've fixed the following warning (generated by pysphere 0.1.8) when such VMs exist:

```
./usr/local/lib/python2.7/dist-packages/pysphere/vi_server.py:317: UnicodeWarning: Unicode equal comparison failed to convert both arguments to Unicode - interpreting them as being unequal
  if v == name:
```

The problem was that pysphere deals with utf8-encoded strings rather than unicode strings, so the unicode string passed in from a RobotFramework test specification is now utf8-encoded before being compared with the string returned by pysphere.

FYI, my text editor is also configured to strip trailing whitespace when saving a file :-)