Use URLS as defined in GetCaps for CSW operations.  #154

Changes the OperationsMetadata objects in ows.py to allow for multiple
urls of the same type (ie. POST/XML and POST/SOAP).
Use utf-8 encoding in CSW requests.
Fix 'id' parameter in CSW's GetRecordById
Allow vendor-specific args in WMTS tile requests.
Merge pull request #156 from kwilcox/master

Use URLS as defined in GetCaps for CSW operations.  #154
Add support for TileMatrixSetLimits.
Update test scripts.
Cope with inconsistent WMTS spec.
Re-instate `tilematrixsets` as deprecated.
Merge pull request #158 from rhattersley/wmts-kwargs

Allow vendor-specific args in WMTS tile requests.
Merge pull request #155 from rhattersley/limits

Add support for TileMatrixSetLimits.
Merge branch 'wmts-docs' of https://github.com/rhattersley/OWSLib into mergeme

Conflicts:
	owslib/wmts.py
Merge branch 'wmts-docs'
Document vendor-specific kwargs.
Merge pull request #160 from rhattersley/document-vendor-kwargs

Document vendor-specific kwargs.
Overload class constructors with empty md (#159)
iso object can be initialized as empty (#159)
Added support for gmd:CI_Citation/gmd:identifier/gmd:RS_Identifier needed by INSPIRE