arrow

ARROW-498 [C++] Add command line utilities that convert between stream and file.

These are in the style of unix utilities using stdin/stdout for argument passing.
This makes it easy to chain them together and I think are using for getting started
or testing. As an example, this command line tests a round trip:
 $ build/debug/file-to-stream /tmp/arrow-file | build/debug/stream-to-file > /tmp/copy
 $ diff /tmp/arrow-file /tmp/copy

If we had the same in java, this would make it pretty convenient for integration
testing.

Author: Nong Li <nongli@gmail.com>

Closes #302 from nongli/utils and squashes the following commits:

b970c75 [Nong Li] fix long -> int64_t
a01ef4d [Nong Li] Fix style issues.
da3d98d [Nong Li] ARROW-498 [C++] Add commandline utilities that convert between stream and file.