Toplevel collection typecheck.

Change-Id: I4a59d1b9391adb84f4a29520a179f8cdbc61e18d
Do not produce extra whitespaces on Python 2.7.3.

Also, make the version check hopefully less cryptic.

Change-Id: I516ed7aa7b8c3a7f005997e7287c68de52eed54c
Heavy Job Plugin support added

This plugin allows you to define "weight" on each job,
and making each job consume that many executors

Change-Id: Iee49229b0d3c909f320caa9bd6c1ebb6bc37ddcb
allow missing reports for HTML publisher

The plugin support a new flag, allow-missing-report. Expose it in jjb.

Change-Id: I026db9e54fdd3be47b74ae709770e6e4f5a77f6e
Closes-Bug: 1277118
Merge "allow missing reports for HTML publisher"
Merge "Heavy Job Plugin support added"
Merge "Do not produce extra whitespaces on Python 2.7.3."
Merge "Toplevel collection typecheck."