Moved passenger gem into the production group, and unicorn-rails into development
tell travis bundler not to fetch production gems
tell travis to retry bundler 7 instead of 3 times.

failures often occur when rubygems times out
rejigging migrations slightly with respect to treatments

to regain consistency between seek and vln-seek.
If treatment_type_id already exists, then it is renamed to measured_item_id instead of being dropped.
add incubation_time and incubation_time_unit_if they don't exist.