bundle update ruby-prof

[ci skip]
Update to jeweler 2.0.1
Fix specs for boys function
Add specs for boys function

[ci skip]
Use Taylor series expansion in Boys function evaluation
Update bundler
bundle update
Update versions of ruby tested on Travis CI
Use autotest-notification instead of autotest-growl
Clean rdoc directory

[ci skip]
Use debugger and byebug
Unify duplicate entries in Gemfile
Remove the dependency on backports gem
autotest: Gemfile.lock invokes all tests
Bundle update
Skeleton for ruphy_libint2 extension
Fix improper CLEAN target addition
Find libint2 library
Use extconf.h
Define module RuPHY::Libint2