Comment 8 for bug 1582513

OK, I've played around a bit and am sort of happy with how I modified the plugin (feel free to review btw). The pull request is up here:

https://github.com/ubuntu-core/snapcraft/pull/510

This has some advantages:

- smaller snaps as we use the system python
- no weird -dev packages being staged that need manual tunning to get out of what was brought in (your actual issue).

$ ls -lh gmailfilter_0.0.1a_amd64.snap
-rw-rw-r-- 1 sergiusens sergiusens 144K may 23 18:33 gmailfilter_0.0.1a_amd64.snap