Created 'context' as synonym for 'describe'

Often this will be used to describe child contexts, so the word context
may seem a better fit. Describe would be better suited to describe a
specific feature, and perhaps it can be refactored, so the framework
implicitly can construct the SUT.

E.g.
describe<ResendPasswordFeature> ...
    context "user already exists" ...
    context "user does not exist" ...