MFH: r419306: deskutils/gcalcli: Fix for oauth2client > 1.4.12

gcalcli requires a dependency on oauth2client <= 1.4.12 to work
correctly, as higher versions replaced the run() method with run_flow().

The version of oauth2client in ports is 2.2.0 at the time of writing.

Fixes for the issue [1][2][3] have been submitted upstream in multiple
cases, although upstream has closed them as duplicates of a refactor
issue [4] that is yet to be committed/resolved.

This commit commits the proposed change in issue #229 [2].

While I'm here:

• Explicitly specify (and limit) supported Python versions to -2.x
• Add python to CATEGORIES
• Group, re-order and sort USE{s}, NO_* and files/plist sections
• Capitalize OPTIONS descriptions

[1] https://github.com/insanum/gcalcli/pull/211
[2] https://github.com/insanum/gcalcli/issues/229
[3] https://github.com/insanum/gcalcli/issues/244
[4] https://github.com/insanum/gcalcli/issues/165

PR: 206045
Submitted by: Lawrence Chen <beastie tardisi com>
Approved by: portmgr (maintainer timeout, 6+ months)

Approved by: ports-secteam (blanket)