Master disconnection can crash slaves

[ggreer]

Error:
[TypeError: Cannot read property 'db' of null]
Stack:
TypeError: Cannot read property 'db' of null
    at Object.all_workspaces (/data/releases/colab-2015_04_05_0957/lib/slave/slave.js:80:14)
    at MasterHandler.send_workspaces (/data/releases/colab-2015_04_05_0957/lib/handler/master        at /data/releases/colab-2015_04_05_0957/node_modules/async/lib/async.js:570:21
    at /data/releases/colab-2015_04_05_0957/node_modules/async/lib/async.js:249:17
    at /data/releases/colab-2015_04_05_0957/node_modules/async/lib/async.js:125:13
    at Array.forEach (native)
    at _each (/data/releases/colab-2015_04_05_0957/node_modules/async/lib/async.js:46:24)
    at async.each (/data/releases/colab-2015_04_05_0957/node_modules/async/lib/async.        at _asyncMap (/data/releases/colab-2015_04_05_0957/node_modules/async/lib/async.        at Object.map (/data/releases/colab-2015_04_05_0957/node_modules/async/lib/async.    Colab stopped
Fuuuuuuuck. Colab died!