Create snaps for sas2ircu, sas3ircu, megacli when supported

[Alvaro Uria]

Per discussion at [1], vendors binaries require apparmor permissions that are not currently supported by snaps plugs.

Once, new interface(s) are available to support strictly confined snaps, do it (and uncomment snap.install line on lib/utils/tooling.py:install_tools [2].

I've pushed a simple version of the snaps at [3][4][5], which require to be "classic" (confinement) and can be installed via "snap install snapfilename.snap --classic --dangerous".

1. https://forum.snapcraft.io/t/request-for-classic-confinement-sas2ircu/9023
2. https://git.launchpad.net/hw-health-charm/tree/src/lib/utils/tooling.py#n39
3. https://code.launchpad.net/~nagios-charmers/hw-health-charm/+git/snap-megacli
4. https://code.launchpad.net/~nagios-charmers/hw-health-charm/+git/snap-sas3ircu
5. https://code.launchpad.net/~nagios-charmers/hw-health-charm/+git/snap-sas2ircu

[Xav Paice (xavpaice)]

We will not be able to redistribute the snaps via the store, but this still has value. Marking wishlist for now.