Redirect single-parent adopters to adoption-specific employment questions
Modify copy of employment questions to not specify mother/principal adopter
Fix earnings_text_start_date plugin execution
Capitalize Birth label on the circumstances question page
Fix lower earnings limit copy in partner's employment question
Redirect single parent adopters to leave_1_adoption not leave_1
Merge pull request #1176 from alphagov/spl-plugin-issues

SPL copy changes and plugin issues