Roll src/tools/swarming_client/ 281c39019..9a518d097 (8 commits)

https://chromium.googlesource.com/infra/luci/client-py.git/+log/281c390193ec..9a518d097dca

$ git log 281c39019..9a518d097 --date=short --no-merges --format='%ad %ae %s'
2018-06-16 maruel [swarming] Implement NamedCache.cleanup()
2018-06-16 maruel [client] Fix 3 issues for the cost of one CL
2018-06-15 maruel [client] Fix cache LRU coherency
2018-06-15 maruel [client] Fix Memory CAC to be LRU, internal cleanups
2018-06-14 maruel [client] cache the named cache size; stop keeping empty caches
2018-06-14 maruel [client] Update lru.py and test
2018-06-13 maruel [client] Refactor the caches to stop using context manager
2018-06-13 iannucci [swarming] Actually apply pool based TaskTemplates.

Created with:
  roll-dep src/tools/swarming_client

TBR=qyearsley@chromium.org

Bug: 801046, 824832
Change-Id: Id2dd2bc2b0295d96726eb200f6e9a0cc8aea1eb7
Reviewed-on: https://chromium-review.googlesource.com/1103534Reviewed-by: Marc-Antoine Ruel <maruel@chromium.org>
Commit-Queue: Marc-Antoine Ruel <maruel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#567906}

DEPS

@@ -113,7 +113,7 @@ vars = {
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling swarming_client
   # and whatever else without interference from each other.
-  'swarming_revision': '281c390193ec8c02e60279f8dac1b86ac52fa4be',
+  'swarming_revision': '9a518d097dca20b7b00ce3bdfc5d418ccc79893a',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling ANGLE
   # and whatever else without interference from each other.