Default NPS slider configuration is biased

Even though the NPS configuration on the production database is configured for a minumum value of 0 and a maximum value of 10, the UI control does not allow a value less than 1 to be entered. This will create an upward skew in our NPS calculations if we assume that a score of 0 is valid.

Additionally, the default value is 6, which is slightly higher than the true medium score. The default should be changed to 5 once the UI slider bug is fixed so that the default answer is a true neutral score.

See also:
https://answers.atlassian.com/questions/167777/why-is-the-help-us-improve-part-of-this-site-a-10-point-scale?page=1#167784