scripts: Improve script file parsing

The script lookup step is now more robust, more resilient against typos
in script names.

Story-Id: SF-99
Change-Id: 07da49944e
Fix Godeps

Story-Id: unassigned
Change-Id: 361c69c971
story changes: Bring the command help up to date

Change-Id: 39d7594b6e
Story-Id: SF-88
story open: Add docs

[ci skip]

Change-Id: 5edebb573c
story changes: Add docs

[ci skip]

Change-Id: d1ee7044dc
story start: Add docs

[ci skip]

Change-Id: caa82112b6
README: Add README links for commands

[ci skip]

Change-Id: 5da1aeb25f
pkg install: Add docs

[ci skip]

Change-Id: da8b6361c0
pkg upgrade: Add docs

[ci skip]

Change-Id: 11325c37f9