RF: simplify and generalize run_mod_cmd

`run_mod_cmd` was getting complicated and it was failing on Windows.
Because it was complicated I couldn't work out why it was failing.
Simplify by writing the script in the temporary directory rather than
trying to use a long command string.  The refactoring may mean that
paths with spaces will work.
BF: use raw strings for Windows paths in script

Windows paths inside the script were not being properly escaped leading to
obscure errors - for example for a path that happened to contain an x after a
backslash.  Use raw strings for variables interpolated into the script.
Merge pull request #202 from matthew-brett/safer-mod-command

RF: refactoring the nisext routines

Make the nisext tester routines simpler to make them easier to debug,
and to fix an error on windows. We should probably deprecate the
testers routines at some point because virtualenvs are a better
solution to this problem, and the buildbot does a fair amount of this
testing.
NF: add set_data_offset method to Analyze headers

To help proxy API tests, and for completeness
DOC: update docstrings for arrayproxy and helper

Fill out API doc while thinking about API testing.

Another tiny docstring update.
RF: apply_read_scaling fix for integer slope/inter

``apply_read_scaling`` should be able to cope with integer slope and
intercept values, although we aren't using these in the code-base yet.
TST: add arrayproxy API validators

Add API validators for the basic arrayproxy uses (Analyze types, MGH
format).
RF: proxy uses header fields, deprecate header copy

Plan not to copy header for the array proxy. Copy out the relevant
header fields and do scaling in the proxy.
TST: add some tests for Ellipsis and fileslice

Confirm that appending None (newaxis) to an Ellipsis appends a new axis.
NF: add coverage / coveralls for travis build

Adapted from https://github.com/scipy/scipy/pull/2907
Merge pull request #204 from matthew-brett/add-coveralls

TST: add coverage / coveralls for travis build

Add automatic coverage report using coveralls

Adapted from scipy/scipy#2907
Add function to save FreeSurfer annotation files.
Add a test for FreeSurfer annotation file writing.
Add test coverage for reading FreeSurfer annot files with
orig_inds=True after they are written with write_annot.
Merge pull request #206 from ohinds/save_annot

Add function to save FreeSurfer annotation files.
DOC: whitespace clean for orientations
RF: refactor general proxy API into own class

Put general API testing into its own class ready to test other array
proxy classes (such as MINC)
NF: add read-only shape to Minc array proxy

Writing API validators revealed shape was not read-only.
RF: rename test for minc2

Test still had minc1 naming
TST: add minc1 / minc2 proxy tests

Use generalized test framework to add minc1, minc2 array proxy tests