Add error handlers for parser errors

[dries]

Currently there is an unhandled error event when syntactically incorrect multipart data is sent by the client which causes node.js to crash. This PR adds basic handlers that allow the node server to live on.

events.js:160
      throw er; // Unhandled 'error' event
      ^

Error: Part terminated early due to unexpected end of multipart data
    at /var/www/web/server/node_modules/dicer/lib/Dicer.js:65:36
    at _combinedTickCallback (internal/process/next_tick.js:67:7)
    at process._tickCallback (internal/process/next_tick.js:98:9)

[coveralls]

Coverage increased (+0.1%) to 95.349% when pulling 0713f6f on dries:master into b9ee66e on richardgirges:master.

[coveralls]

Coverage increased (+0.1%) to 95.349% when pulling 0713f6f on dries:master into b9ee66e on richardgirges:master.

[richardgirges]

Solid 👍