Squashed 'core/' changes from f111d77..432cfe8

432cfe8 Plugin Debian packages
973584b Prepare Debian package for plugins
3a3df6a Prepare dput for plugin usage
01c9445 Make debuild-signed.sh reusable
c078fe4 Make changlog perl script more universal
eba5680 Make more abstract internal event bus
99ffdd6 Update undertow
858a5c0 Extract Inno Setup code.iss to make it usable in GUI installer
000baa2 Gradle script update to make it work with gui plugin
a9c3039 Fix build
0cacbdf Simplify external events (don't expose too many internal objects)
02fe473 Merge branch 'develop' of github.com:syncany/syncany into develop
1718555 Move events
b0fe4bd Update CHANGELOG.md

git-subtree-dir: core
git-subtree-split: 432cfe891703f63dc7ae1db1b6c1d028259c57a8
Merge commit 'd35c0065a7fbea6dec5f369a02f06506dc4c969b' into develop
Debian package