Add support for newdmd in get_about_memory.py.

If DMD is running, get_about_memory.py will trigger dumping of DMD info.  This is then filtered through fix_b2g_stack.py, which symbolicates the stacks.
gitignore fix_b2g_stack's persistent cache.
Make get_about_memory.py wait longer before giving up, since dumping DMD files can take a while.
During flash.sh, remove any regular files on the device which aren't in dist/b2g on the host.
Make run-gdb.sh detect DMD and pass the appropriate args to b2g.
Bug 817166 - Make update-tools work when .userconfig has echo statements in it

More specifically, redirect the output of .userconfig to stderr so its still seen
by the user.
Merge pull request #185 from dhylands/dhylands-817166-update-tools

Bug 817166 - Make update-tools work when .userconfig has echo statements... r=marshall
When running DMD inside GDB, use sample-below=4096.

This is /much/ faster.
Fix typo in comment in fix_b2g_stack.py.
Add comment in flash.sh explaining why we need delete_extra_gecko_files_on_device.
Tweaking comments in fix_b2g_stack.py.
DMD now takes --sample-below= instead of sample-below=; updating run-gdb.sh to match.
Merge pull request #184 from jlebar/newdmd

Add support for newdmd (bug 717853)
Bug 821086 -  Modify run-gdb.sh to work with MOZ_DEBUG_APP_PROCESS
Merge pull request #186 from dhylands/dhylands-821086

Bug 821086 -  Modify run-gdb.sh to work with MOZ_DEBUG_APP_PROCESS r=mwu
Update fix_b2g_stack.py to handle the change in format from bug 819833.
Update run-gdb.sh to use new DMD defaults.

DMD=1 is now equivalent to DMD="--sample-below=4093".
Bug 822970 -  Change config.sh to default to the nightly branch. r=cjones

r=cjones on IRC
Merge pull request #187 from dhylands/dhylands-822970

Bug 822970 -  Change config.sh to default to the nightly branch. r=cjones
Fix get_about_memory.py so it runs fix_b2g_stack.py on Linux.