Add gitignore file with common types
Add run_tests script, run automatically in Travis

Add a test runner script which runs any units tests using nosetests
(there currently aren't any) and will eventually run PEP8 tests.

This will run on Travis CI after visiting https://travis-ci.org/profile and
enabling it for the repo.

In Travis CI, we need to use system site packages for numpy and scipy,
see:
http://danielnouri.org/notes/2012/11/23/use-apt-get-to-install-python-dependencies-for-travis-ci/

For Travis to try to install the right packages (not numpy/scipy),
create two requirements files: `requirements/_common.txt` and
`requirements/_numpy_and_scipy.txt`.

As a developer, you can install `./requirements.txt`. As Travis, you can
install `./requirements_for_travis.txt`

In the `.travis.yml` file we also use the environment variables for
ATLAS, BLAS etc as suggested by Sam in the README:

```
export LAPACK=/usr/lib/liblapack.so
export ATLAS=/usr/lib/libatlas.so
export BLAS=/usr/lib/libblas.so
```
Apply PEP8 style guide to Python files

- tide.py
- constituents.py
- astro.py
- nodal_corrections.py

http://legacy.python.org/dev/peps/pep-0008/
Merge branch 'add-travis-tests'
Merge branch 'apply-pep8-to-tide-py'
Add Observations & CsvObservations classes

The purpose of these classes is to make an easy way to load observation
data (datetime, height) from a source such as CSV, and handle any
wrangling to ie numpy when required.

- `Observations` is an abstract-base-class defining a basic interface
  which all subclasses must adhere to.
- `CsvObservations` reads observations from an arbitrary-sized CSV with
  UTC dates.

See also the tests for CsvObservations which capture its behaviour.
Add test to capture the output of known analysis

This is a regression test to pin the behaviour of pytides doing a full
analysis for `example_observations_1.csv`

Note that it depends on the new `CsvObservations` class.
Merge branch 'add-observations-class-and-tests'
Merge branch 'add-regression-test-for-example-tide-prediction'