Copy debug PNaCl plugin in Dev builds of the chromoting webapp.

Copy debug PNaCl plugin in Dev builds of the chromoting webapp.

With this change the Debug version of the PNaCl plugin will be copied to
the webapp directory allowing to debug PNaCl plugin (using nacl-gdb).

Also updated build-webapp.py to process all *.jinja2 input files as jinja2
templates.

This patch was previously reverted because of a problem that should be
fixed now by https://codereview.chromium.org/872673006/ .

BUG=451643
Committed: https://crrev.com/a0f666219c0a8e03e2fd4909cb5fab8859a49462
Cr-Commit-Position: refs/heads/master@{#314873}

[Sergey Ulanov, 2015-01-24 00:35:04]

sergeyu@chromium.org changed reviewers:
+ jamiewalch@chromium.org

[Jamie, 2015-01-24 00:50:02]

LGTM

[Sergey Ulanov, 2015-01-24 18:07:49]

The CQ bit was checked by sergeyu@chromium.org

[commit-bot: I haz the power, 2015-01-24 18:08:50]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/872633006/1

[commit-bot: I haz the power, 2015-01-24 18:52:04]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-01-24 18:53:05]

Patchset 1 (id:??) landed as
https://crrev.com/65ffdafc8538b14ad0cbdf6a57d9d21e1e882a9d
Cr-Commit-Position: refs/heads/master@{#313024}

[Sergiy Byelozyorov, 2015-01-24 19:29:53]

A revert of this CL (patchset #1 id:1) has been created in
https://codereview.chromium.org/870273002/ by sergiyb@chromium.org.

The reason for reverting is: Broke compile, e.g.
http://build.chromium.org/p/chromium/buildstatus?builder=Win&number=28337.

[Sergey Ulanov, 2015-02-05 20:58:20]

The CQ bit was checked by sergeyu@chromium.org

[commit-bot: I haz the power, 2015-02-05 20:59:40]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/872633006/1

[commit-bot: I haz the power, 2015-02-05 21:00:59]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-02-05 21:01:55]

Patchset 1 (id:??) landed as
https://crrev.com/a0f666219c0a8e03e2fd4909cb5fab8859a49462
Cr-Commit-Position: refs/heads/master@{#314873}