Updates in Context order

Small change that fixes cleanup order, and a bit of refactoring.

Changes:
  * order values in rally.benchmark.context.cleanup.context
    set to maximum value, so this cleanup runs first after scenario
    is finished. That avoids blocking of context resources deletion
    by resources that created by scenarios.
  * change some resources order so they are not immediately follows
    after each other: 301, 302, 303 -> 310, 320, 330.

Change-Id: Id195d7df6cb369d448f8a0019891a693a0d3d0aa
Merge "Updates in Context order"