Validate *values* of ALMA queries

Final update to the UI, I hope - validates query *values* now too:

```
Alma.query(payload={'energy.frequency-asu':'5..1'})
Traceback (most recent call last):
  File "<ipython-input-3-9d21fba8506d>", line 1, in <module>
    Alma.query(payload={'energy.frequency-asu':'5..1'})
  File "/Users/adam/repos/astroquery/astroquery/utils/class_or_instance.py", line 24, in <lambda>
    f = lambda *args, **kwds: self.fn(obj, *args, **kwds)
  File "/Users/adam/repos/astroquery/astroquery/utils/process_asyncs.py", line 28, in newmethod
    response = getattr(self, async_method_name)(*args, **kwargs)
  File "/Users/adam/repos/astroquery/astroquery/alma/core.py", line 131, in query_async
    self.validate_query(payload)
  File "/Users/adam/repos/astroquery/astroquery/alma/core.py", line 163, in validate_query
    "{0}".format(bad_kws))
InvalidQueryError: Invalid query parameters: {'energy.frequency-asu': '{"energy.frequency-asu":"org.eso.asu.parser.ASUVisitorException: failed to parse \\"5..1\\" as float"}'}
```

(the correct way to specify a frequency range is `1 .. 5`, with the space