Improve add user workflow and default location

[timlinux]

Problem

Currently the map always zooms to your current location on first load. This is not what we want - rather the work flow should be:

• User opens the page, it zooms to global extent showing both users and devs
• User clicks a small 'add me' button beneath the [+][-] buttons in the zoom box
• Map zooms to user's approximate location and location ring is show (as is currently already implemented)
• When user moves mouse over map a cross hair cursor is show providing a visual hint that clicking will add a point.
• Once the point is confirmed, layers should refresh and the temporary blue marker should be replaced with the standard user_map markers

  Proposed solution:

• [ ] See http://leafletjs.com/reference.html#icontrol for notes on how to add a new control
• [ ] Implement the workflow as described above

  Expected outcomes:

• Map defaults to global view
• Adding user is an explicit action that must be pre-empted by a button click in the control box
• After adding themself, user should see map updated with user data and pan mode should be reinstated.

[akbargumbira]

Problem in L.Control and click that control but it fires onClickMap and drag the map:

• Issue: https://github.com/Leaflet/Leaflet/issues/1343
• Solution: https://github.com/Leaflet/Leaflet/blob/master/src/control/Control.Zoom.js#L46

[akbargumbira]

The implementation of the problem above is here: 1b7014291e1e843ffa6377a6335856ed98139793

[akbargumbira]

Hi @timlinux , I think I have implemented all this workflow. Please take a look.

[timlinux]

Yeah its working great thanks!