fix(metadata, saveDataset): create specialized input components and add functions to get metadata editor to work without bugs and play well with new qri api

[ramfox]

closes #347 Hidden rows on datasets closes #342

• [x] ValidLicenseInput fixed
• [x] create ValidCitationsInput
• [x] create ValidContributorInput

closes #339 closes #348 closes #344

[ramfox]

Note to self before running to meeting: purecomponents are awesome but there are pitfalls, make sure to examine in ValidCitationsInput.js