Revert "Lowercase all usernames"

Author: dbkr

src/components/structures/login/Registration.js

@@ -302,7 +302,7 @@ module.exports = React.createClass({
         } : {};
 
         return this._matrixClient.register(
-            this.state.formVals.username.toLowerCase(),
+            this.state.formVals.username,
             this.state.formVals.password,
             undefined, // session id: included in the auth dict already
             auth,