Add Report Bug Button within Light Table

This is a fix in response to issue #125. There has been a button added to the Light Table Welcome Screen that allows the user to click and report issues on GitHub. There is also a "Report an Issue" Help menu item that allows the user to do the same. 

![reportissuebrowser](https://f.cloud.github.com/assets/5749454/2260625/dae829b0-9e43-11e3-8d6a-c1539845e63d.png)