Add the most useful Apache Commons utils

Add the most useful Apache Commons utils


R=brianwilkerson@google.com
BUG=
TEST=

Committed: https://code.google.com/p/dart/source/detail?r=7049

[Brian Wilkerson, 2012-04-26 20:00:18]

LGTM, except that, if I understood the conversation in the stand-up correctly,
we want to replace the file header with the same one used in the rest of the
compiler code.

[scheglov, 2012-04-26 20:33:17]

On 2012/04/26 20:00:18, Brian Wilkerson wrote:
> LGTM, except that, if I understood the conversation in the stand-up correctly,
> we want to replace the file header with the same one used in the rest of the
> compiler code.

We can not _replace_ copyright header.
According to Apache License "4.Redistribution.(c)"
"      (c) You must retain, in the Source form of any Derivative Works
          that You distribute, all copyright, patent, trademark, and
          attribution notices from the Source form of the Work,
          excluding those notices that do not pertain to any part of
          the Derivative Works; and"

So, I've added Dart copyright header, but keep also previous Apache header.