Show default value using placeholder text
Lighten placeholder text
Clear text when setting is changed to default
Don't change text unless the value it parses to changes

Previously entering something like `2.` in a field would parse to
2 which would set the value to 2 in the config which would then change
the editor text to `2`.

Now the value in the editor view is only changed when the value it parses
to is different from the current value.
Add Travis badge
Use build script from atom/ci repo
Merge pull request #111 from atom/ks-show-default-value-as-placeholder-text

Show default value as placeholder text