'Nonce does not match' error when state data contains '=' encoded as %3D

[BLevinger]

This issue occurs when btoa appends an '=' to the stringfy data object for base64 encoding. The state data then contains a %3D encoded character after it round trips from IDP login which causes TransactionManager to attempt to locate the transaction as 'ASDF%3D' instead of 'ASDF='

	    this.auth0.authorize({
			connection: authProviders.google,
			redirectUri: document.location.protocol + "//" + document.location.host + "/register",
			state: 'ASDF='
		})
}

Issue can be resolved by adding the following on line 51 of transaction-manager.js

transaction = transaction.replace(/%3D/ig, '=')

Occurs in chrome v56

[BLevinger]

I've updated my own code to strip the padding character. Not sure this should be fixed in auth0 as = should not be passed in the first place but I am seeing btoa include it.

[hzalaz]

We should handle the url decoding since the state comparison is done by auth0.js.

[hzalaz]

Closed by #382