add support for qualified named attribute in ecql

[jokiefer]

add support for qualified named attribute in ecql like dc:title LIKE '%huhu%'

fixes #22

[constantinius]

I think when referencing properties that include characters like : one has to properly quote them with double quotes. "dc:title" LIKE '%huhu%'. I'll need to read up on the spec in that regard.

[constantinius]

@jokiefer I'm sorry I mixed up the specs. In the CSW spec we see various examples of property identifiers with the colon character without quoting. e.g taken from the CSW 2.0.2 spec:

http://www.someserver.com/csw/csw.cgi?request=GetRecords&version=2.0.2&outputFormat=application/xml&outputSchema=http://www.opengis.net/cat/csw/2.0.2&namespace=csw:http://www.opengis.org/cat/csw&ResponseHandler="mailto:[email protected]"&typeName=csw:Record&elemnSetName=brief&constraintlanguage=CQLTEXT&constraint="csw:AnyText Like '%pollution%'" 

[constantinius]

In CQL 2 Text colon characters only seem to be allowed at the start of the identifier (which is weird, imo): https://github.com/opengeospatial/ogcapi-features/blob/master/cql2/standard/schema/cql2.bnf#L228