v2.2.0.rc1

This is a release candidate. It will become Solidus 2.2.0 if no issues are reported

on rubygems
on github

Changes since v2.2.0.beta1

• Use can_complete? instead of confirm? to check if Order can be completed #1833 (mamhoff)
• Fix sidebar vertical alignment #1845 (tvdeyen)
• Fix centering of pagination under bootstrap 4.0.0.alpha6 #1844 (jhawthorn)
• Fix date range filter under firefox #1846 (jhawthorn)