Fix issue with keys ending to dot '.'

- match_to_key method adds '*' at the end of the key, which makes
  valid_key? to return false, since '*' is not in the list of valid
  characters defined in VALID_KEY_RE
- because the key is invalid, it is ignored
Consider keys ending to : as an expression
Merge pull request #90 from sharetribe/dynamic-fix

Dynamic keys are ignored due to the asterisk at the end of the key