BREAKING CHANGE: The request method of Proxy class now accepts and returns axios-specific values
BREAKING CHANGE: The default value of keepAlive setting has been changed to true
* Before it was throwing immediately which meant we weren't parsing the protocol and weren't showing the proper error responses
* If proxied W3C error doesn't have an error, make it `Unknown Error`
* Previously, we were only checking the HTTP payload to see what protocol should be
* This is inadequate, in the case of drivers that don't proxy W3C Capabilities yet
* The fix now is to set the protocol in `createSession` to see if the W3C caps were proxied through, if they're not, set protocol to MJSONWP
* Added unit test and one e2e test to confirm that this works
* Convert JSONWP proxy errors
* Previously, if a proxied response has a status code >= 0 but http status code 200, the error is thrown but it's an unknown error because the 'getResponseForW3CError' function doesn't translate the error
* Now, it translates the JSONWP error using logic we already have that accomplishes this
* Added E2E test that tests a proxy that returns 200 but status 7 to check that it throws the correct ElementNotFoundError
* Added unit test to handle the new case in 'getResponseForW3CError'
* Do proxying for W3C responses
* If a W3C Response is provided by a proxy, map to the correct error
* Checks if `value` is an object and `value.error` and maps it based on that (`value.error` is the W3C error code)
* Broke off `errorFromCode` into `errorFromMJSONWPStatusCode` and `errorFromW3CJsonCode`
* Rename '.error' property to correct W3C property
* The error property in the ProtocolError objects should match up with https://www.w3.org/TR/webdriver/#handling-errors under the 'JSON Error Code' column
* Added tests for all of these
* Make ProxyRequestError work for W3C
* Added an arg called `.w3c` that passes in the proxied W3C error
* Fixed the `getActualError` function that looks for the .w3c variable and parses error from the code
* Rename 'mjsonwp' to 'protocol'
* Renamed folder from 'mjsonwp' to 'protocol' in `lib/` and `test/`
* Renamed 'mjsonwp.js' to 'protocol.js'
* Renamed any import statements that use 'mjsonwp'
* _Possible breaking change_: MJSONWireProtocol class exposed in index was renamed to just Protocol.... checked Appium repo and found no libraries that use MJSONWireProtocol
* Lint fix
