Sending exit message to devtools to exit.

Accepted and closed incoming streams

Added header to for constant use.

Removed extra spaces.

Corrected spacing to conform to coding standards.

Corrected spacing to conform to coding standards.

Corrected spacing to conform with coding standards.

Moving new import next to old import for devtools_traits as specified in comment.

Removed method definition to include as inline code and changed to iter_mut.

Using loops to exit devtools on server exit message and disconnected message to simply break as suggested in the comment.

Removing TODO comment for completed functionality.

Moved the operation for exit of devtools on servo closing outside the match loop.

Removing trailing ';' and adding new line before connection closing loop.
auto merge of #3796 : shanil-puri/servo/ServoExitDevtools, r=jdm