Added a maximum version to Distribution().

I encountered an incompatibility when part of the build (zinc) picked
up java 1.8 in my path instead of java 1.7. This change by itself
does not fix the issue, but lays some foundation to help pick a
distribution less than a maximum rev.

Signed-off-by: John Sirois <jsirois@twitter.com>
Remove ability to configure workdir locations.

There's no need to be able to override the location of task workdirs,
and this allows us to be rid of a bunch of flags and pants.ini keys.

After this change we compute a unique workdir per task instance, based
on the phase/goal it's registered under, and plumb that through
the task's __init__(). That did require changing __init__'s signature
on all tasks, but it made for more straightforward code.

While at it, I also fixed a bunch of superclass __init__ invocations
to use super().

This change affects many files (every task at least has its
__init__() signature changed) but the changes are mostly tiny.
Get rid of some configurable outdirs.

In these tasks it makes sense to hardwire the outdir to
be the workdir. Allowing it to be customized via flags seems
like unnecessary overkill, especially when it comes to intermediate
build products like generated code.
Upgrade jmake to 1.3.8-1.

commit c9e81c08db5be5074009d9414206f355d9a90017
Author: John Sirois <jsirois@twitter.com>
Date:   Mon Apr 28 10:35:56 2014 -0600

    Upgrade jmake to 1.3.8-1.

    Also fixes old twitter-commons cache dir name.

 BUILD.tools                       | 2 +-
 build-support/ivy/ivysettings.xml | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

Testing Done:
$ ./pants goal test tests/{java,scala}::
...
10:35:03 00:12           [jmake]
                         warning: bootstrap class path not set in conjunction with -source 1.6
                         Jmake version 1.3.8-1
                         Writing project database...  Done.

10:35:05 00:14         [find-missing-dependencies]
...
10:35:15 00:24   [test]
10:35:15 00:24     [junit]
10:35:15 00:24       [bootstrap-junit]
10:35:16 00:25       [run]
                     .......
                     Time: 0.165

                     OK (7 tests)

10:35:17 00:26     [specs]
               Waiting for background workers to finish.
               SUCCESS

Bugs closed: 85

Reviewed at https://rbcommons.com/s/twitter/r/282/
Get rid of the remaining 'outdir' flags.
Get rid of conditional imports of markdown and pygments.
Ensure that zinc analysis from cache is correctly merged.

This is a probable fix for the missing-class-at-runtime bug.