add bug reporting feature to help page

To aid in debugging individual user issues and bugs, it would be helpful if data regarding the Piwik install and server were sent to us along w/ a bug report. A new section can be added to the Help page that allows users to either:

• send such a bug report w/ info
• view the bug report to copy-paste in a dialog (so they can report to the forums or email it themselves)

The following info can be helpful in debugging:

• phpinfo() output
• server info (OS, filesystem, etc.)
• webserver log entries related to piwik install
• Piwik log entries from a certain time (should also allow users to manage logging through the web interface so we can get as much debug info as possible)

Users should be able to specify which info to send and should be able to double check that they are ok w/ sending the data.