QConnection misshandles connection failures

[buckie]

If the QConnection attributes are bad (i.e. the q server isn't up or the port number is wrong) it's handled incorrectly. Should only take an error catch in https://github.com/exxeleron/qPython/blob/master/qpython/qconnection.py#L115-L119 to fix the issue.

# kdb is running on port 5000
In [1]: from qpython import qconnection

In [2]: q = qconnection.QConnection('localhost', 5000)

In [3]: q.open()

In [4]: q.is_connected()
Out[4]: True

In [5]: q = qconnection.QConnection('localhost', 6000)

In [6]: q.open()
---------------------------------------------------------------------------
error                                     Traceback (most recent call last)
<ipython-input-6-486c86d6f873> in <module>()
----> 1 q.open()

/Users/wjm/repos/qPython/qpython/qconnection.pyc in open(self)
    106                 raise QConnectionException('Host cannot be None')
    107
--> 108             self._init_socket()
    109             self._initialize()
    110

/Users/wjm/repos/qPython/qpython/qconnection.pyc in _init_socket(self)
    116         '''Initialises the socket used for communicating with a q service,'''
    117         self._connection = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
--> 118         self._connection.connect((self.host, self.port))
    119         self._connection.settimeout(self.timeout)
    120

/Users/wjm/anaconda/envs/flask-kdb/lib/python2.7/socket.pyc in meth(name, self, *args)
    222
    223 def meth(name,self,*args):
--> 224     return getattr(self._sock,name)(*args)
    225
    226 for _m in _socketmethods:

error: [Errno 61] Connection refused

In [7]: q.is_connected()
Out[7]: True