Implement new page to select the maturity before checkout
merge branch 'master' into jl-new-select-maturity

Conflicts:
	app/locales/pages/projects/contributions/new.en.yml
	app/views/projects/contributions/new.html.slim
Merge pull request #633 from neighborly/jl-new-select-maturity

 Implement new page to select the maturity before checkout