snap: general improvements

Refer-to: Selective-checkout: Check out the tagged release revision if it isn't promoted to the stable channel - doc - snapcraft.io <https://forum.snapcraft.io/t/selective-checkout-check-out-the-tagged-release-revision-if-it-isnt-promoted-to-the-stable-channel/10617>
Refer-to: Releasing your app - Documentation for snaps: Universal Linux packages <https://docs.snapcraft.io/releasing-your-app/6795>
Signed-off-by: N林博仁(Buo-ren Lin) <Buo.Ren.Lin@gmail.com>

Signed-off-by: N林博仁(Buo-ren Lin) <Buo.Ren.Lin@gmail.com>

This patch allows the snap to use the latest Snapcraft features.
Signed-off-by: N林博仁(Buo-ren Lin) <Buo.Ren.Lin@gmail.com>

show sensors alias in web interface

snap: Support canonical config paths, fixes #1403

snap: Add packaging-specific gitignore rules

snap: Fix broken --webserver due to missing network-bind plug

Update cmds.rst

Ignore loop back file systems under Ubuntu

sensor aliases currently work in the curses interface, but not in the
web one

fixes #1456

This patch supports canonical config paths by the help of the
`personal-files` and the `system-files` security confinement interfaces.
Signed-off-by: N林博仁(Buo-ren Lin) <Buo.Ren.Lin@gmail.com>

This should drop the -dirty tag in the snap version string.
Signed-off-by: N林博仁(Buo-ren Lin) <Buo.Ren.Lin@gmail.com>

Signed-off-by: N林博仁 <Buo.Ren.Lin@gmail.com>

Fix `--modules-list`

This hides about a dozen loop back file systems on my Ubuntu 18.04 machine, cleaning up the side bar tremendously.

First commit with basic function. The plugin is to large. The default bahavor should be bar. Sparkline should be activated uppon --sparklines tag

switch back to timestamp el name, clean up verbiage

Add NEWS file for ElasticSearch: add date to index, unbreak object push (thanks to @genevera) # 1438