Add a switch to allow passing --gcov-tool to lcov (which can now be llvm-cov if using CLang) Refs #4008
store arg as string rather than list. References #4008
Converting "Problem" to a shared_ptr
refs #4009, #3698
Converting "Executioner" to a shared_ptr
refs #4009, #3698
Merge pull request #4030 from milljm/coverage

build_coverage script can now handle clang coverage
Merge pull request #4031 from permcody/problem_ptr

Converting "Problem" to a shared_ptr
Start working on DerivativeTwoPhaseMaterial (#4035)
AddArg to move phi into args (#4035)
Implement derivatives (#4035)