save username and display name in local storage

[dpocock]

JSCommunicator provides a way for users to log in with arbitrary SIP credentials (see the way it is used at https://rtc.debian.org )

Each time a user visits the site, they have to type

• their display name (e.g. Daniel Pocock)
• their SIP address (e.g. [email protected])
• their password

We should avoid keeping the user password in any cache or local storage. However, maybe the display name and SIP address can be saved in local storage. It may be a good idea to provide a checkbox where the user can confirm that they want those details remembered in the browser they are using.

[dpocock]

This has been implemented in Juliana's commit.

Note that if a username or display name is provided in the config file, that will take priority and cached values will not appear in the login form.

This logic should also ensure that in situations where no login form is displayed (because the password is preconfigured), arbitrary values from the local storage will not conflict with the values mandated by the configuration.

One side effect is that the boxes can no longer be pre-configured to say "Your name here" or some other hint.

The remember-me checkbox could be improved further by #49, #50 and #51