Climata

* Add support for EPA's WQX domain values service (e926c92)
* Fix issue with `snotel.StationHourlyDataIO` (14)
* Drop Python 2.7 from tests due to a unicode translation issue (71cddaa). For most use cases the library should still work fine in Python 2.

- Fix MethodNotFound error due to evaluating `_server` as boolean (11)
- Fix OWSLib dependency (12, 13)
- Misc fixes and code cleanup

- Python 3 support (9)
- Preliminary support for a number of NWS forecast formats (8)

- Test suite and [Travis CI](https://travis-ci.org/heigeo/climata)
- Compatibility with [wq.io 0.6.0](https://github.com/wq/wq.io/releases/v0.6.0) and [requests 1.3.0](https://github.com/kennethreitz/requests/releases/tag/v2.3.0) (7)

This release adds support for the [NRCS SNOTEL AWDB](http://www.wcc.nrcs.usda.gov/web_service/awdb_web_service_landing.htm) SOAP services (2).

This release adds support for [USGS NWIS](http://waterdata.usgs.gov/nwis) webservices (1).

In addition, all of the main `climata` IO classes now include metadata indicating which location, parameter, and time-based filters they support. Specifically, every class subclassing `climata.base.WebserviceLoader` explicitly declares support (or non-support) for the following init arguments:
- `start_date`, `end_date`: requested date range
- `state`: Two letter state code
- `county`: 5-digit FIPS code (except for CocorahsIO which uses a two-digit code)
- `basin`: 8-digit Hydrologic Unit Code
- `station`: One or more site identifiers (service-specific)
- `parameter`: One or more parameter

Some classes accept the arguments ignore them, others require them, and others accept multiple values in a list or tuple format. The `get_filter_options()` method can help determine usage.

This metadata is used by the new [climata-viewer](https://github.com/heigeo/climata-viewer) project, an interactive website for requesting and downloading time series data from climata-supported webservices.