Fixed Python setup bug. Now the setup script works with Python version 2.6+
Lint fix + dep analysis fix.

- Fixed bug in reporting missing deps on synthetic targets.
  Synthetic targets frequently create trivial dependency cycles. (like
  specific message types depend on "messageset", and "messageset" depends
  on the message types) In order to avoid tripping the cycle detector, they
  don't declare the deps that cause the cycle. As a result, we shouldn't
  report missing deps errors that don't break a compile for synthetic targets.
- Added support for intransitive dependency to fixlint.

Auditors: benjy
Lint fix + dep analysis fix.

- Fixed bug in reporting missing deps on synthetic targets.
  Synthetic targets frequently create trivial dependency cycles. (like
  specific message types depend on "messageset", and "messageset" depends
  on the message types) In order to avoid tripping the cycle detector, they
  don't declare the deps that cause the cycle. As a result, we shouldn't
  report missing deps errors that don't break a compile for synthetic targets.
- Added support for intransitive dependency to fixlint.
Merge branch "lintfix" back to master.
fix pants command and add a link to homepage
Merge pull request #131 from imsut/README_update.2

fix pants command and add a link to homepage
Merge branch 'master', remote-tracking branch 'origin'
Merge remote-tracking branch 'twitter/master'
Updated file following feedback from @jsirois.

1. PY variable handles the path to python.
Fixed one line that I left out by mistake: python -> $PY.
Merge pull request #129 from hwasungmars/master

Minor bugfix on Python version detection.
Fix source deps bug in dependency analysis.

- Not all dependencies were getting computed correctly, because the source_deps section
 of the analysis relations file wasn't getting used. (It was removed because it appeared
 to be redundant, and caused some trouble with error message generation.) This reinstates
 source_deps in the analysis.

Auditors: benjy
Merge pull request #130 from ryan-williams/paths

Add "path" and "paths" goals for finding dependency paths between targets
add default arg for context.py requested_goals
Merge pull request #132 from ryan-williams/default-arg-fix

add default arg for context.py requested_goals
Make java artifact caching less sloppy.

Also make creating the processors info file happen even
when we pulled from the artifact cache.
Fix invalidation bugs.

1) Delete the hash-file before building a target, so that if
   the build aborts and leaves the output dir in a bad state
   and then we revert the change, we force a rebuild.

2) Ensure hashes are computed consistently.
Make missing dep errors actual errors.

Remove some commented-out code that wouldn't even work
any more if it were uncommented.

Auditors: markcc
Revert "Make missing dep errors actual errors."

This reverts commit b5f47ae1cc4b5889b8a50bfd767e7848cca275f4.
Fix scala artifact merging bug.