Fixes some typos and formatting.
Resolve conflict in `test` command options

`-r` was short for both `--root-url` and `--reporter`. In reality,
it was always parsed as `reporter`.
Now its shortcut just for `--root-url` to be consistent with `gather`.

Closes #85
Merge pull request #81 from bem/feature/docfixes

Typos and formatting
Error message when crop region exceeds screenshot

Previously, gemini would simply fail in this case with
'Bad arguments' error. Now extensive message will be shown
with a list of possible workarounds. Only one state will fail
in this case without interrupting the whole testing process.
Merge pull request #88 from bem/fix/crop-error

Error message when crop region exceeds screenshot
Put coverage templating logic into separate module
Add coverageNoHtml option
Merge pull request #90 from bem/feature/ext-coverage

Put coverage templating logic into separate module
0.9.2
Follow symlinks when resolving css paths