Add `slc arc` command

The command corresponds to `strong-arc` from `strong-arc`.
Merge pull request #181 from strongloop/feature/add-arc

Add `slc arc` command
Add optional dependency on sl-blip

URL will be updated when released with `slt-release`.

See strongloop-internal/scrum-nodeops#201
Merge tag 'v2.9.3'

2.9.3

 * Add optional dependency on sl-blip (Ryan Graham)
Include git commits in version output if available
package: use debug v2.x in all strongloop deps
Upgrade all simple dependencies
package: update strong-arc to ^1.x
v2.10.0
Merge branch 'release/2.10.0' into production