implementing builder for external commands
using command builder for flake8
adding shortcut for conditional arguments with formatting
using shortcut for conditional arguments with formatting
implementing execution of external commands
adding license headers
refactor has_argument -> use_argument, thx @aelgru
removing useless property

build is verbose and this already includes making flake8 verbose
using execution result in flake8 plugin
improving the flake8 error handling
Merge pull request #67 from pybuilder/feature/cli-builder

Adding a command line builder for plugins using external commands