memoize `./pants path` lookups

it was dumbly not re-using previous work
memoize `pants paths`

split out path and paths implementations; they need to work
differently to each be as fast as possible
Fixup the PrepareResources task to properly augment the classpath in
the exclusives regime.

Undo pingpong example workaround.

Perform minor cleanups on exclusives related code read to grok this
fix.
Remove a superfluous encode() call.

dist.get_metadata() returns a string (NOT a unicode). It is not
logically sound to call encode('utf-8') on a string, only on a
unicode. In fact, string probably shouldn't have an encode() method
at all.
Merge pull request #174 from foursquare/master

Remove a superfluous encode() call.
Merge pull request #171 from jsirois/jsirois/pants/issue_160

Fixup the PrepareResources task to properly augment the classpath in the exclusives regime.
Revert "Keep the && chain alive in the travis build, a failed pants build should fail fast."

Eric knew what he was doing here of course :/

This reverts commit cf28c12cf8c9f63174ee07d56ed76873baf57d9a.
Merge remote-tracking branch 'origin/master' into ps
review feedback
more review feedback
Merge pull request #133 from ryan-williams/paths

Paths
Fixed ZooKeeperNode to prevent duplicate WatcherS

Duplicate WatcherS were being added on failed getData calls
because a new Watcher was passed into the getData call each time. This
change creates a Watcher that is .equals so that the Set of Watchers
within the ZK library doesn't grow when there are request failures.
WatcherS are now instance fields

applied feedback from @jsirois
Merge pull request #177 from foursquare/fs-zk-20130819

Fixed ZooKeeperNode to prevent duplicate WatcherS
Support osx 10.9.
Merge remote-tracking branch 'twitter/master'
raise URLError when CachedWeb gets non-200 code

This is to stop bad responses from being put into the python cache.
Merge pull request #22 from jeffjenkins/py-cache-error

raise URLError when CachedWeb gets non-200 code
Remove lazy initialization in TokenizedCharSequence
Remove unused imports.