Introduced configuration settings with xhrForm; currently
config.namesToHashes is observed: when set to true element names in the
form "element_name[element_index]" will result in an object hash
"element_name": { "element_index": <value> } sent to the server

Change-Id: I601a0ef03a89df6b2b434b004b004fb4ed9d8146
Bugfix: values of element names with hashes were wrapped in erroneous
extra objects; fix needs some more testing and perhaps optimization

Change-Id: Ie668bab2b545af8b71779f594660f8bf2ad07792
Added simple cookie library, lifted from
https://developer.mozilla.org/en-US/docs/Web/API/document.cookie

Change-Id: I5d922d099e57c33ec9bf43f352ea2208f5db5685