obspy.iris: Use new FDSN web services and retire deprecated services

The IRIS DMC has implemented the International Federation of Digital Seismograph Networks (FDSN) versions of their core web services that support access to time series data, related metadata and event parameters.  The equivalent DMC services are now deprecated and will be retired, read more on that at http://www.iris.washington.edu/pipermail/webservices/2013-March/000378.html.

* The fdsnws-dataselect service returns selected time series in miniSEED format: http://service.iris.edu/fdsnws/dataselect/1/
* The fdsnws-station service returns selected station metadata in FDSN StationXML and text formats: http://service.iris.edu/fdsnws/station/1/
* The fdsnws-event service returns selected event parameters in QuakeML and text formats: http://service.iris.edu/fdsnws/event/1/

The FDSN web services are available from a dedicated host name with new web documentation: http://service.iris.edu/

### Deprecation of equivalent IRIS services

With the release of the FDSN services they are deprecating the equivalent services.

These services will be turned off in approximately 6 months:

 * ws-bulkdataselect (http://www.iris.edu/ws/bulkdataselect)
 * ws-dataselect (http://www.iris.edu/ws/dataselect)
 * ws-station (http://www.iris.edu/ws/bulkdataselect) 
 * ws-event (http://www.iris.edu/ws/event) 


### Differences between FDSN and the services they are replacing

The FDSN web services return HTTP status code 204 to indicate "No data" as opposed to status code 404 used by the services they are replacing.  The behavior of returning a 404 can be restored by including the 'nodata=404' parameter and value in the request.

**fdsnws-dataselect** is a combination of the capabilities of ws-bulkdataselect and ws-dataselect:

 1. enhancement: the network, station, location and channel selections may be comma-separated lists (e.g. BHE,BHN)
 2. enhancement: the network, station, location and channel selections may contain * and ? wildcards
 3. should be a drop-in replacement for ws-bulkdataselect (accepts the same requests via POST).
 4. a near complete replacement for ws-dataselect (accepts GET requests with parameters) except that it does not support the 'ref' parameter and does not support caching in the internal ICAB system.

**fdsnws-station** is equivalent to ws-station with these important changes:
 1. the XML output is returned as FDSN StationXML, a different schema
 2. new 'matchtimeseries' parameter to limit results to channels with high probability of data at the DMC
 3. the 'output' parameter name is changed to 'format'

The FDSN StationXML schema (http://www.fdsn.org/xml/station/) is generally equivalent to the XML format previously used but it is a distinctly different schema that cannot be parsed with the same software parsing the XML from ws-station.

**fdsnws-event** is equivalent to ws-event with these differences:
 1. the FDSN service returns event depths in meters to conform to QuakeML 1.2 (the ws-event service used kilometers)
 2. the 'output' parameter name is changed to 'format'
 3. only a single catalog can be selected per-request, the default catalog is 'NEIC PDE'
 4. in addition to the default order of descending results, the 'orderby' parameter can be 'time-asc' or 'magnitude-asc' to set the order to ascending.