Clarify libev version and pyev workaround
Merge pull request #8 from joaquincasares/update_dep_instructions

Clarify libev version and pyev workaround
Add scales to install_requires
Basic Metrics class initialization
Documentation for metrics attributes
Add a request_timer attribute to Metrics
Add methods for incrementing counters
Hook into metrics when enabled
Remove connection pool metrics from TODO list
Ignore .so and egg-info
No more bare excepts
Stop asyncore loop from complaining about a bad socket

Stops:
```
Exception in thread event_loop:
Traceback (most recent call last):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/threading.py", line 552, in __bootstrap_inner
    self.run()
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/threading.py", line 505, in run
    self.__target(*self.__args, **self.__kwargs)
  File "/Users/matt/Dropbox/python-driver/cassandra/io/asyncorereactor.py", line 27, in _run_loop
    asyncore.loop(timeout=0.001, use_poll=True, count=None)
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/asyncore.py", line 214, in loop
    poll_fun(timeout, map)
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/asyncore.py", line 144, in poll
    r, w, e = select.select(r, w, e, timeout)
error: (9, 'Bad file descriptor')
```
Don't yell on __del__

Was getting:
Exception TypeError: "'NoneType' object is not callable" in <bound method Session.__del__ of <cassandra.cluster.Session object at 0x109128c90>> ignored
Default to using pyev if we can
Same here as well
Merge pull request #9 from mattrobenolt/bare-excepts

No more bare excepts
Merge pull request #10 from mattrobenolt/gitignore

Ignore .so and egg-info
Merge pull request #12 from mattrobenolt/typeerror

Don't yell on __del__
Merge pull request #13 from mattrobenolt/defaultconnection

Default to using pyev if we can
Log the exception to debug