fix lengths

[tarmo888]

Text should be as long as modern tweets (280 chars) and longer than any data (profile, poll, attestation) limits, otherwise someone wanting to timestamp some text would just post it as some other type, which has higher limit.

• changed text limit from 140 to 280 and made textarea as high as the definition text area.
• some inputs had ng-maxlength and maxlength, some only ng-maxlength. made all have both.

These changes Tony copy-pasted from my Pull Request:

• added character limit to poll question, previously only poll options were limited.
• fixed profile/attestation key and value lengths to match lengths in constants.js
• fixed datafeed value length to be limited to 64 while keeping the raw data value to 256.