Auditing: Add rails_best_practices checks to Travis build, do cleanup

[kevinrobinson]

This adds a subset of https://github.com/flyerhzm/rails_best_practices, does cleanup on the items it found, and adds the check to the Travis build.

These include:

• removing unused methods
• calling ActiveRecord operations and ignoring the return value (change to bang methods)
• removed some old rake tasks related to schools (synced differently now)

Some other config was just noise, so those are disabled here in rails_best_practices.yml.

EDIT: I also looked at UseBeforeFilterCheck which seems potential useful but is too noisy.

This also updates administrate to be more explicit, and limit open routes as helpfully pointed out by RestrictAutoGeneratedRoutesCheck.

# removed
admin/educators#create
admin/educators#new
admin/educators#destroy

# kept, explicitly now
admin/educators#index
admin/educators#show
admin/educators#edit
admin/educators#update

[kevinrobinson]

example of how failures look in the build:

[kevinrobinson]

selfie