= servlet: add termination awaiting to Initializer::contextDestroyed

[TulioDomingos]

Release memory by making sure all threads are stopped before app undeployment takes place.

More info at:
https://groups.google.com/forum/#!topic/spray-user/4wwQbHFXkxk
https://groups.google.com/forum/#!topic/akka-user/Lp2hn4FfhU8

[sirthias]

Tulio, great, thanks for this fix!

Two things we'd need before we can merge this:

1. Can you accept the Typesafe CLA?
2. Please rephrase the commit message to:

= servlet: add termination awaiting to `Initializer::contextDestroyed`

(in accordance with our commit message policy)

[TulioDomingos]

Done!

[jrudolph]

Have you checked that it works, @TulioDomingos ? Otherwise, it looks simple enough to me. 👍

[sirthias]

Thanks for accepting the CLA!
Could you also update the commit message?

[TulioDomingos]

@jrudolph Yep, it works! The following errors don't show up in Tomcat anymore

SEVERE: The web application [/spray-template_2.10-0.1] appears to have started a thread named [example-scheduler-1] but has failed to stop it. This is very likely to create a memory leak.

SEVERE: The web application [/spray-template_2.10-0.1] appears to have started a thread named [example-akka.actor.default-dispatcher-2] but has failed to stop it. This is very likely to create a memory leak.

[jrudolph]

Excellent. Thanks again.

[TulioDomingos]

You're welcome. Cheers!