Add custom become matcher for acceptance tests
Move locale helper out of step definitions
Article should have a canonical tag
Article should have a alternate tag
Use article localised cassettes

The content of the page is changing when we change the language. We need to save different cassettes to be able test this changes
Alternate value for Welsh cassette is English
Remove postfix conditional
Replace 'specify' by 'it'
Merge branch 'article-meta'