arrow

ARROW-312: Read and write Arrow IPC file format from Python

This also adds some IO scaffolding for interacting with `arrow::Buffer` objects from Python and assorted additions to help with testing.

Author: Wes McKinney <wes.mckinney@twosigma.com>

Closes #164 from wesm/ARROW-312 and squashes the following commits:

7df3e5f [Wes McKinney] Set BUILD_WITH_INSTALL_RPATH on arrow_ipc
be8cee0 [Wes McKinney] Link Cython modules to libarrow* libraries
5716601 [Wes McKinney] Fix accidental deletion
77fb03b [Wes McKinney] Add / test Buffer wrapper. Test that we can write an arrow file to a wrapped buffer. Resize buffer in BufferOutputStream on close
316537d [Wes McKinney] Get ready to wrap Arrow buffers in a Python object
4822d32 [Wes McKinney] Implement RecordBatch::Equals, compare in Python ipc file writes
a931e49 [Wes McKinney] Permit buffers (write padding) in a non-multiple of 64 in an IPC context, to allow zero-copy writing of NumPy arrays
2c49cd4 [Wes McKinney] Some debugging
ca1562b [Wes McKinney] Draft implementations of Arrow file read/write from Python