Remove Password field from OAuth signup page

This removes a bit of friction.

Ref T715 T712

pages/signup-oauth.tmpl

@@ -95,12 +95,6 @@ form dd {
 <input type="text" name="email" style="width: 100%; box-sizing: border-box;" placeholder="Email"{{ if .Email }} value="{{.Email}}"{{ end }} />
                     </dd>
                 </label>
-                <label>
-                    <dt>Password</dt>
-                    <dd>
-<input type="password" name="password" style="width: 100%; box-sizing: border-box;" placeholder="Password" /><br />
-                    </dd>
-                </label>
                 <dt>
                     <input type="submit" id="btn-login" value="Login" />
                 </dt>