Add ability to view stacktraces of all threads when the exception is captured

[haroldadmin]

It is helpful to view the stacktraces of all active threads during the time an exception is thrown. Representing each thread's stacktrace in a list of collapsible items would make it easy to go through each one of them.

Tasks:

• Capture all active stacktraces using the [Thread.getAllStackTraces()](https://docs.oracle.com/javase/7/docs/api/java/lang/Thread.html#getAllStackTraces()) API in the exception handler
• Parse the captured values and send them over the service connection
• Create an accordion-style list to display the stacktrace of each thread

This is a fairly huge change. Discussing exact UI implementations would be helpful before starting work on the PR.