Remove unnecessary Boost dependencies and update documentation

[simogasp]

• Remove unnecessary Boost libraries: atomic, chrono, system , thread and math_c99
  • this is in anticipation of the deprecation of findBoost: only non-header libraries are associated with targets, the header-only must be included via target_include_directories(). This is a bummer because we lose track of the components that are actually used.
• Update the INSTALL documentation with the badges, README, and other doc with markdown linting.
• Removed old travis ci files aa7b7f1

[philippremy]

Hi! Quick question: IIRC Boost provides the special target Boost::headers for all its header libraries. Would it make sense to use that instead of setting the include dirs manually?