Feature client api function

refs #92 

Modified the api augment function such that if 2 parameters are passed (resource,callback) the fragment is set to {}.
If 2 callback functions are passed
``` 
client.api("data.api").watch("/foo", callback1, callback2)
```
 only the first is accepted ie:
```
client.api("data.api").watch("/foo",callback1)
```