* Fixed a defect in 'firstMatch' validation
* Previously, it was validating the firstMatch capabilities and was failing on the first validation failure, which is a problem if firstMatch has a length > 1 and it fails before finding a potentially passing capabilities set is found
* Now, it doesn't error-out on the first failure. If it fails, it skips over it to the next one until it finds one that passes and returns that.
* Altered the 'presence' constraint validation
* Don't validate 'presence' on 'alwaysMatch' because if a capability isn't present on 'alwaysMatch' it may be present in one of the 'firstMatch' capabilities
* Validate presence on all of the 'firstMatch' capabilities, except for the keys that are present in 'alwaysMatch'. If the key is in 'alwaysMatch', strip out the presence constraint because we know that it has passed already
* Changed the default protocol
* If MJSONWP _and_ W3C are provided, initiate a W3C session by default. If clients are passing in W3C parameters to create a session, we can safely assume that they've implemented the rest of the W3C spec
* Improved error logging
* If errors were found, show a message saying `Could not find matching capabilities: ${errors}` where `errors` are a list of all the validation error messages for each of the attempts to validate `firstMatch` caps
* If `firstMatch` caps has a length of one, then don't show the message saying `Could not find matching capabilities` portion of it, just show the errors
* Other remediations
* Allow `alwaysMatch` and `firstMatch` to be `null` or `undefined`
* Added single quotes around names of capabilities when showing their errors
* Remember protocol requested in createSession
* Also renamed 'processCaps' to 'processCapabilities'
* Checks the parameters in 'createSession' and determines if it's W3C or MJSONWP
* Add W3C error format
* Add W3C status codes to errors
* When deciding error format to return in mjsonwp.js, check format and then return eitherJSONWP or W3C format
* Added a test for unzipFile (which uses adm-zip)
* Tested that it worked with adm-zip and then failed once adm-zip was taken out
* Replaced 'adm-zip' with zip.extractAllTo from appium-supprt
dan@saucelabs.com