simplify download button
smaller download button with context on dash

To use bitmask services:
Download Bitmask
remove os specific download buttons

keeping the platform detection for now.
adopt pricing view to current service_level format
remove outdated os detection test
upgrade debugger so it works with p545 on travis
Merge pull request #155 from azul/feature/simplify-download-btn

Feature/simplify download btn
Merge pull request #154 from azul/feature/display-pricing

adopt pricing view to current service_level format
hide srp forms when no js is available

Hiding them using two mechanisms in case one fails:
.hidden class - bootstrap hides them then
style='display:none' - so they are hidden even if css load fails
minor: fixing comment