Cosmopy

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- Added redshift to comoving-, luminosity-, and angular-diameter- distance methods.
- Added differential volume calculation (dVc/dz)

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- Added colored output using the 'click' package (added to dependencies).
- Added significant unit-testing. Coverage currently at 98%.
- Added function documentation.

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- Fix issue with version file. Use hardcoded version strings in both `setup.py` and `__init__.py` for now.
- Fix python2-python3 incompatibility issue regarding use of `super`.
- Added `future` package to requirements to deal with this.
- Improve the README usage documentation.

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- Fix install issues from missing 'requirements' file (wasn't being loaded properly in 'setup.py').
- When no arguments are given, explain that arguments are required and print help message.
- Added version (and other metadata) info to '__init__.py'.

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- Renamed everything from `cosmocalc` to `cosmopy` (former already taken on pypi).
- Added travis and coveralls integration and badge-icons.
- Command-line input is parsed using astropy to identify input units.
- API functions added to retrieve cosmological parameters via python method calls.
- Can also retrieve underlying `Cosmology` instances directly.

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- Completely restructured and rewrote code to use an `astropy.cosmology.FlatLambdaCDM` subclass for bulk of cosmological calculations. This class uses stored grids of distance measures to perform interpolation when inverting from a distance measure to a redshift.
- The basic functionality is working in which an input redshift, scale-factor, distance (lum or com), of time (age or lookback) can be input, and all of the other parameters will be calculated and printed.


- cosmopy/
- __main__.py
- This provides the entire API for command-line accessible functions (at the moment).
- `parse_input()` [NEW-FUNCTION]
- Take an input string which specifies a quantitative value and convert it into a usable numerical object using `astropy.units.Quantity`.
- `calc()`
- Runs all of the basic cosmological calculations.
- `output()`
- Format and print the resulting values.
- cosmology.py [NEW-FILE]
- Cosmology [NEW-CLASS]
- Currently uses fixed set of cosmological parameters (i.e. Omega values) and calculated distance measures.
- tests/ [NEW-FOLDER]
- test_main.py [NEW-FILE]
- Added a few very simple tests for parsing input values.

- parameters.py [DELETED]
- settings.py [DELETED]