Ditch `%s` string formatting in assertions
Ditch `%s` string formatting in `VowsAssertionError` class
Tweaked `VowsAssertionError` class

* added a few sanity checks
* instance variable `msg` is now `raw_msg` (suggesting that it is intended for use with `str.format()`)
Made `Vows.create_assertions` friendly to `str.format()`
Minor improvements to `VowsReporter.print_traceback()` (in `reporting.common`)

* every time I read “exc_blah”, I think “**execute** blah” instead of “**exception** blah”.  So I renamed these to “err_blah”. :-P
* Also renamed `err_value` to `err_obj`, since it more accurately describes what the variable contains
* Also, this method was manually indenting its output; changed to use the `indent_msg()` method
Merge pull request #71 from Zearin/refactor/VowsAssertionErrors

Refactored VowsAssertionErrors
Replaced uses of `map()` with list comprehensions

I didn’t realize that `map()` was considered “outdated” until Pylint pointed it out.  *shrug*

As it turns out, I find the list comprehensions far easier to understand.
`README.mkd` → `README.md`

It’s the most commonly used suffix, so…
Tidied profile results list code
`--long_cli_option` → `--long-cli-option` (underscores are annoying)
Merge pull request #72 from Zearin/feature/misc_cleaning

* Small code tweak
* Command-line options are now `--underscore_free`–er, I mean…`--underscore-free`! :tongue:
Move class-level attributes to top
Expanded docstring of `VowsResult`
Minor code clarity tweak
Minor code clarity tweaks (and comments)
Alphabetized standard lib imports

…and aligned imports for assertions package.
Minor code clarity tweaks
Don’t `pprint` results! :o
Minor refactoring of `VowsTestReporter`
Tidied up `VowsTestReporter` printing

This also required a few edits to the base class `VowsReporter`.

This, in turn, required a minor edit to a test (`tests/bugs/64_vows.py`).  (In the test, the lambdas arguments count must equal the corresponding methods in `VowsReporter`.)