added optional requirements

Merge pull request #1709 from nicolargo/dependabot/npm_and_yarn/glances/outputs/static/elliptic-6.5.3

Bump elliptic from 6.4.0 to 6.5.3 in /glances/outputs/static

Set cpuinfo version to 4.0.0 until issue https://github.com/workhorsy/py-cpuinfo/issues/155 is analysed

Bumps [elliptic](https://github.com/indutny/elliptic) from 6.4.0 to 6.5.3.
- [Release notes](https://github.com/indutny/elliptic/releases)
- [Commits](https://github.com/indutny/elliptic/compare/v6.4.0...v6.5.3)
Signed-off-by: Ndependabot[bot] <support@github.com>

Merge pull request #1708 from nicolargo/dependabot/npm_and_yarn/glances/outputs/static/lodash-4.17.19

Bump lodash from 4.17.15 to 4.17.19 in /glances/outputs/static

Bumps [lodash](https://github.com/lodash/lodash) from 4.17.15 to 4.17.19.
- [Release notes](https://github.com/lodash/lodash/releases)
- [Commits](https://github.com/lodash/lodash/compare/4.17.15...4.17.19)
Signed-off-by: Ndependabot[bot] <support@github.com>

Merge pull request #1707 from nicolargo/dependabot/npm_and_yarn/glances/outputs/static/macaddress-0.2.9

Bump macaddress from 0.2.8 to 0.2.9 in /glances/outputs/static

Bumps [macaddress](https://github.com/scravy/node-macaddress) from 0.2.8 to 0.2.9.
- [Release notes](https://github.com/scravy/node-macaddress/releases)
- [Commits](https://github.com/scravy/node-macaddress/compare/0.2.8...0.2.9)
Signed-off-by: Ndependabot[bot] <support@github.com>

Add RSS metric for containers

Since Resident Set Size is available for containers, an additional column has been added to display this value.

Looks like the stats were removed because they where gone in Docker 1.11. This change put them back since they've been available again for a while now.