Adding connection handler

Added a class for handling the Redis connection & application level namespace for the keys.  The application namespace allows different applications / services to utilize the same Redis instance without key collisions.

Redistat can then be configured with the following: 

```
$redis = Redis.new
Redistat::Connection.establish_connection($redis, 'app1')
```
or
```
Redistat::Connection.redis = Redis.new
Redistat::Connection.namespace = 'app1'
```

with the namespace being optional in the establish_connection method.

Also added a couple changes to get travis to work.