Support Ruby 2.0 syntax

- Add integration test analysing a sample file with Ruby 2.0 syntax
- Depend on ruby_parser version with Ruby 2.0 support
Added feature to remove extra slash from source path to prevent doubling of slash character in report output.

Printing line numbers is now the default behaviour from the command line.

Reverse commit
Merge branch 'default_line_numbers' of https://github.com/gilles-leblanc/reek into default_line_numbers

Conflicts:
	features/reports/reports.feature