Test code with both unicode_literals and without
First pass at resolving issues when testing with/without unicode_literals
Remove redundant test_*_unicode.py files
Get FITS warning collection working again.
Move to whitelisting
Turn on unicode literal testing in select test files.
Document the TEST_UNICODE_LITERALS tag.
Fix some tests that only fail when running in parallel.
Fix more issues with parallel testing
Document why the test fixtures are defined in conftest.py
add missing bsddb in python stdlib to known_issues
line ending/whitespace
Slightly clearer error message for `len` of a scalar coordinate object
Added `shape` to coordinates
Add test for shape on coordinates
update changelog
Add docstring to shape property
Fix merge snafu
Add `one` as shortcut to `dimensionless_unscaled`

I find creating dimensionless `Quantity`es overly painful compared to quantities with dimensions. Currently the two existing options are:

1. Putting `u.km`, `u.s` next to `u.dimensionless_unscaled`. Too large.
2. Putting `u.km`, `u.s` next to `u.Unit('')` or `u.Unit(1)`. Why the inconsistency?

I find dimensionless quantities very convenient, and hence this tiny addition. It's the shortest and least obstrusive way I found to use them.

```
a = 1.0 * u.AU
ecc = 0.0167 * u.one
inc = 0.0 * u.deg
...
```
Moved u.one, added test and entry in CHANGES.rst