new feature: return all intermines over version x

Sometimes applications need to fetch all InterMines, but only above (or below) a certain version, to avoid calling features that don't exist, or to take advantage of newer features. IT would be nice to ask the registry to only return InterMines of the version we want.

A useful API call to the registry might look something like this:

http://registry.intermine.org/service/instances?version_api=gte-25
http://registry.intermine.org/service/instances?version_api=lt-24
http://registry.intermine.org/service/instances?version_api=eq-24

http://registry.intermine.org/service/instances?version_intermine=gte-2.0.0
http://registry.intermine.org/service/instances?version_intermine=lt-1.6.6
http://registry.intermine.org/service/instances?version_intermine=eq-4.0.0

the operators I've suggested above are:

```

gt (greater than)
gte (greater than or equal to)
lt (less than)
lte (less than or equal to)
eq (equal to)

```

Additionally, note that there are several different version strings returned by InterMines. Visit http://iodocs.apps.intermine.org and look at flymine, then search for the version endpoint. Here's a quick summary:

GET /version returns the API version. This is a int.
GET /version/release returns the version of the data release for that InterMine (and will be a string with arbitrary content)
GET /version/intermine returns the version of InterMine (as in the Java application). This looks like a number but is a string in semantic versioning format, e.g. "4.0.0".

/version/release and /version/intermine are newer endpoints, and older InterMines, such as Indigo, won't respond to them correctly - they'll return the int response, same as /version does. See http://www.cbrc.kaust.edu.sa/indigo/service/version/intermine for an example. Checking the response data type will give you an hint about which InterMines this happens in.

FINAL note - we should probably sort on API version and InterMine version, but the release version endpoint, given that it's arbitrary string data, won't be sortable, so it wouldn't make sense to have a filter for it.