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
Use config.reportDir when storing reports/images
Modify config to include reportDir
Better error handling

Now with stack traces.
Remove redundant code.
Merge pull request #8 from Whizy/errorreporting

 Error reporting improvements.
add stub for client.performance function

This function is called regularly by the client for non-godly players.
Merge pull request #9 from yelworc/client-performance

add stub for client.performance function