benchmarks(crazyflie): crazyflie plant
doc(README.md): add coverity scan badge
fix(opensmt/smtsolvers/SMTConfig.c): assign initial value to nra_json (false)
fix(opensmt/smtsolvers/SMTConfig.c): assign initial value to nra_ODE_timeout (0.0)
chore: have bin/dReal in addition to bin/solver
fix(opensmt/smtsolvers/SimpSMTSolver.C): resource leak(file)
chore(dsolvers/icp_solver.cpp): fix indentation
fix(dsolvers/icp_solver.cpp): memory leak
new benchmarks: quadcopter stabilizer, underwater vehicle
chore(travis): disable ocaml tool compilation for OSX build

It has x11 dependency and causes compilation problem for now.
chore(travis): disable ocaml tool compilation for OSX build