Broader exception catching for ES collector http call

Hi,

Even catching URLError was not enough. Collecting metrics during ES restart sometimes hits the httplib.BadStatusLine exception (subclass of http.HTTPException).

But to be sure I changed the except to any Exception. Let's get this over with :-)

```
[2013-12-16 16:16:34,921] [Thread-1] Traceback (most recent call last):
  File "/usr/lib/python2.6/site-packages/diamond/collector.py", line 390, in _run
    self.collect()
  File "/usr/share/diamond/collectors/elasticsearch/elasticsearch.py", line 227, in collect
    + 'indexing=true&get=true&search=true')
  File "/usr/share/diamond/collectors/elasticsearch/elasticsearch.py", line 55, in _get
    response = urllib2.urlopen(url)
  File "/usr/lib64/python2.6/urllib2.py", line 126, in urlopen
    return _opener.open(url, data, timeout)
  File "/usr/lib64/python2.6/urllib2.py", line 391, in open
    response = self._open(req, data)
  File "/usr/lib64/python2.6/urllib2.py", line 409, in _open
    '_open', req)
  File "/usr/lib64/python2.6/urllib2.py", line 369, in _call_chain
    result = func(*args)
  File "/usr/lib64/python2.6/urllib2.py", line 1190, in http_open
    return self.do_open(httplib.HTTPConnection, req)
  File "/usr/lib64/python2.6/urllib2.py", line 1163, in do_open
    r = h.getresponse()
  File "/usr/lib64/python2.6/httplib.py", line 990, in getresponse
    response.begin()
  File "/usr/lib64/python2.6/httplib.py", line 391, in begin
    version, status, reason = self._read_status()
  File "/usr/lib64/python2.6/httplib.py", line 355, in _read_status
    raise BadStatusLine(line)
BadStatusLine
```