Better field name for "refreshed" in "snap info" output

Thanks for working on that, and +1 on the change suggested right above. “refreshed” has a pretty useful meaning which is quite expected too, so change the data and preserving the meaning sounds like the right direction for the fix.

Having the build time wouldn’t be bad either, but can we please call it “packaged” instead? This goes well with “snap pack” and “snapcraft pack”, and also aligns better in the command line, and with the fact snaps don’t really enforce the build time at packaging time.

Speaking of alignment, can we please take this change to do one other change:

$ snap info core
(...)
type:      core
snap-id:   99T7MUlRhtI3U0QFgl5mXXESAiSwt776
tracking:  edge
refreshed: 2018-02-23T01:22:03-03:00
installed:   16-2.31.1+git587.d3e52a0 (4133) 85MB core
channels:
  stable:    16-2.31.1                (4110) 85MB -
  candidate: 16-2.31.1                (4110) 85MB -
  beta:      16-2.31.1                (4110) 85MB -
  edge:      16-2.31.1+git587.d3e52a0 (4133) 85MB -

I see why installed is aligned the way it is, making the comparison with the maps very comfortable, but it also makes the output look messy. We typically skim through such a document top-to-bottom, and those last lines look all over the place, with extra spacing on the left, extra spacing on the right, and then the channel map is indented.

A trivial change could perhaps sort this out, preserving compatibility:

type:      core
snap-id:   99T7MUlRhtI3U0QFgl5mXXESAiSwt776
tracking:  edge
refreshed: 2018-02-23T01:22:03-03:00
channels:
  stable:    16-2.31.1                (4110) 85MB -
  candidate: 16-2.31.1                (4110) 85MB -
  beta:      16-2.31.1                (4110) 85MB -
  edge:      16-2.31.1+git587.d3e52a0 (4133) 85MB -
installed:   16-2.31.1+git587.d3e52a0 (4133) 85MB core

How does that look?