Equality support in geo queries

[c0c0n3]

PR #111 implements full support for NGSI geo queries. However, queries with the equals geo relationship operator are disabled for the time being---QL responds with a 422 NotSupportedQuery as required by the NGSI spec. The reason for shape equality being disabled is an issue with the underlying Crate query which uses the within function. This function is supposed to support arbitrary shapes but only seems to work when the first argument is a point. We opened an issue in the Crate repo about it. Hopefully it'll get fixed, at which point all we'll need to do is:

• upgrade to the version of Crate containing the fix
• remove these two lines of code

...and voila, geo equality is back in!