Uniformize dependency translation errors.

There was a non-uniform set of exceptions being raised and trapped (or not!)
in the translation call paths.  This unfiromizes Web and CachedWeb to always
raise FetchError when opening urls and then hardens SourceLink and EggLink
to trap for this and re-raise UnreadableLink when attempting link fetches.
Finally, EggTranslator and SourceTranslator now trap Link fetch errors and
log & return None to allow Obtainer to proceed to the next available link if
any instead of failing fast on a bad link.
Merge pull request #219 from twitter/jsirois/python-commons/trap_link_failures

Uniformize dependency translation errors.
Revert PYTHON_VERBOSE=2 used to help debug python_antlr_runtime fetch issues.
Merge pull request #220 from twitter/jsirois/travis-ci/revert-verbosity

Revert PYTHON_VERBOSE=2 used to help debug python_antlr_runtime fetch
A temporary hack to remove generated files from IDEA indexing.
[PATCH 01/16] Don't assume pex files run in envs with PATH

 - PythonInterpreter.all: Allows running pex files in environments
     which do not have PATH set
 - PythonInterpreter.all: Runs os.getenv at call time, not module load
 - PythonInterpreter.replace: Add cls.InterpreterNotFound, which was
     already being raised
 - Make interpreter.py pass checkstyle (v1)

Jira: AWESOME-6981

RB_ID=259385

(sapling split of ac21b861cc06e7996e4766ce94d1ac8667ea62a5)
[PATCH 05/16] fix up a #@namespace

RB_ID=276103

(sapling split of 81ba8b72367cd311904b27c1f882210fef7b9a42)
[PATCH 06/16] Use filename as part of the pex cache key as some eggs have the same checksum on their own. This causes issues for different python interpreter versions.

RB_ID=277815

(sapling split of d58d849ecf77312aa22986622daaf083c7823a2b)
[PATCH 07/16] add update_headroom cronjob

Adds the "update_headroom" cron job.  This job takes the top N jobs in a
cluster by aggregate size and asks the following question: "If we were to
set instances=\infinity and run an update, at which point would it fail to
schedule?" This allows us to determine how close some of our big jobs are
running at redline.  This report is then e-mailed to aurora-sla@twitter.com
every 12 hours.

RB_ID=278635

(sapling split of 54ba49c9ccd11ef5c5ad8bb5a2d7a2fdaffa8810)
[PATCH 08/16] Added option to send DELETE with twitter.common.jira api_call

RB_ID=280839

(sapling split of 8aa21493a9a9275129b75cf7ad33a580e63261dc)
[PATCH 09/16] Increase TunnelHelper default timeout

I bumped it to 5 minutes : only users know when they have waited long
enough.

I changed how the back off works slightly: it doesn't make sense to wait
for multiple seconds between connection attempts, and with the
exponential growth of the timer, it quickly gets to tens of seconds.

RB_ID=282083

(sapling split of 6733fcdf1d1f9dddecf1647affb7268dd33dcb9e)
[PATCH 10/16] tunnel helper shut up shut UP SHUT UP

RB_ID=283053

(sapling split of b00170acec4532b2d33449c14860e3509aa395a2)
[PATCH 11/16] Fix missing methods.

RB_ID=283171

(sapling split of dee6c5313a73e7d85df05bdef63a589f81076482)
[PATCH 12/16] Alphabetize target dependencies This looks like a total yak shave, but it will make automating the moving of dependencies to 3rdparty/... easier.

RB_ID=285621
TBR=true

(sapling split of 3189674498304979ce21dbd2e5165593064f7984)
[PATCH 13/16]  [Storm] AchievementBird notifier with a local Storm test unit

RB_ID=278943

(sapling split of ba18f55d0ba38adeef828184355904f96aa9db4a)
[PATCH 14/16] Add methods to Python twitter.commons.jira lib

RB_ID=284711

(sapling split of 2a649434fefeaee568a0e3ca2209fcbed0670c86)
[PATCH 15/16] Implement twitter.common.http kerberos plugin + examples

RB_ID=284529

(sapling split of 59ccbb77447b03ac91048aced8769acf491b9517)
[PATCH 16/16] [zookeeper][kazoo_group] no need to unchroot() create_async results on >= 1.3

RB_ID=291937

(sapling split of 3bec6fc77fbc1300a8d8c306c1643ee88308b262)
Clarify and cross-reference bundle and resources.

Update the docs for "bundle" and "resources" as users are confused. The former
are loose files in the application bundle, and the latter Java-style resources
accessible via the Class.getResource API.

https://rbcommons.com/s/twitter/r/21/
Squashed commit of the following:

commit 2aa3999398b433b7ca6f246c2700d4a9c644b1c2
Author: Larry Hosken <lhosken@twitter.com>
Date:   Mon Feb 24 13:46:59 2014 -0800

    doc tweak: in hindsight, these not-quite-commons paths were trolls