Reorganize HMC tests and add gradient tests for Hamiltonian tests
Add new files/remove old files
Added energy conservation test
Added test for integrator symplecticness
Careful separation between fixture-dependent and fixture-free tests
updated make to have the test files have a dependency. Makes the build easier.
updating make/tests dependencies
merged makefile changes and updated paths and all tests pass
Merge pull request #341 from stan-dev/feature/more_hmc_tests

Feature/more hmc tests