TileStache build fixes, case sensitive filesystem and vagrant machine

Every commit has its own description and purpose. 

The fixes in this pull request are:

1.- Travis build: 
     - Since the VM used by Travis is using a later linux distribution the packages were failing to install because of the new pip behavior. 
     - The memcache tests were failing to connect to memcache in Travis.

This should address: https://github.com/migurski/TileStache/pull/158 https://github.com/migurski/TileStache/pull/161

2.- Case-insensitive filesystem:
Case-insensitive filesystems were running into errors because of filenames. In my case, it was HFS (set with case-preserving but case insensitive) running a VirtualBox VM. I ran into this issue internally, but other people have also (I noticed because I was browsing other people's forks). https://github.com/migurski/TileStache/pull/172 https://github.com/migurski/TileStache/pull/173 

3.- Vagrant Machine:

Vagrant Machine with TileStache pre-configured and ready to debug. That way we can get up and ready to go with one command:
```bash
vagrant up
```