Explicitly disable parsing JavaScript markup in email bodies

Fixes #78, https://bugzilla.gnome.org/show_bug.cgi?id=713656
4 jobs for wip/disable-js in 26 minutes and 4 seconds
latest
Status Job ID Name Coverage
  Build
passed #422006
ubuntu

00:13:56

 
  Test
failed #422007
flatpak

00:12:07

 
  Deploy
skipped #422008
review
skipped #422009
allowed to fail manual
stop_review
 
Name Stage Failure
failed
flatpak Test
Full log written to /builds/GNOME/geary/_build/meson-logs/testlog.txt
A connection to the bus can't be made
Uploading artifacts...
WARNING: geary-dev.flatpak: no matching files
repo/: found 4475 matching files

_build/meson-logs/meson-log.txt: found 1 matching files

_build/meson-logs/testlog.txt: found 1 matching files

Uploading artifacts to coordinator... ok
id=422007 responseStatus=201 Created token=hb31yqdz
ERROR: Job failed: exit code 1