Add integration tests

[morganastra]

at minimum tests should cover:

• [ ] page for a single pronoun (e.g. pronoun.is/they)
• [ ] page for a pronoun with one and two alternates (e.g. pronoun.is/they?or=she and pronoun.is/they?or=she&or=ze)
• [ ] page for properly described non-database pronouns (e.g. pronoun.is/a/b/c/d/e)
• [ ] error page for improperly described non-database pronouns (e.g. pronoun.is/a/b)
• [ ] front page showing proper list of pronouns
• [ ] junk paths and query parameters give a reasonable error, not an info-free 503