consider have.css_class_containing(partial_name) condition

[yashaka]

Can be useful in cases like this:

where because of some frontend framework specifics all css class names have autogenerated unique ids as suffixes

[yashaka]

Hm... yet we can achieve same via have.css_class('.*errorMessage.*').pattern or even have.css_class('*errorMessage*').with_wildcards that can be implemented in #537