Make error reports viewable
Save error reports and images to the reports dir

client.error now returns the error_id, which can be used in
client.attachErrorImage to attach the image to the report.
Send a slack message on error log creation.

The message includes the link to the full error log.
Stub activity related APIs

This stops errors from being sent when the player opens the "Updates"
window.
Include error image in report if it exists

Attached error image can be found at the bottom of an error report.
Merge pull request #6 from Whizy/errorreporting

Viewable error logs