[Fix #771] Three new cops to replace Style/EmptyLinesAroundBody

In order to make it possible to configure where we
want empty lines and where we don't want them, the
EmptyLinesAroundBody cop is removed and replaced
by three new cops, EmptyLinesAroundMethodBody,
EmptyLinesAroundClassBody, and
EmptyLinesAroundModuleBody. The last two can be
configured to require or disallow empty lines
around the body.
More detailed messages about empty lines
Merge pull request #1399 from jonas054/771_configurable_empty_lines

Configurable empty lines