Fix CSV output of matrices to be in column-major order, consistent with the header output..
Merge branch 'develop' into feature/fix-csv-for-matrices
Fix CSV output of matrices to be in column-major order, consistent with the header output..
Additional unit testing for CSV output of matrices.
Merge branch 'feature/fix-csv-for-matrices' of https://github.com/stan-dev/stan into feature/fix-csv-for-matrices

Conflicts:
	src/test/io/csv_writer_test.cpp
updating display of error code in run_command()
updated run_command() to return an error code; updated all tests that use run_command()
from Michael: feature/fix_model_test_fixture
adding error_codes
changing quotes to <> for includes
adding tests that fail
adding src/test/gm/arguments/test_model to gitignore list
Updated src/test/gm/command_test.cpp and src/test/gm/arguments/argument_parser_test.cpp to pass
updating model_test_fixture to run test-models
working on argument_configuration_test
updating unit / model tests
Fix behavior of remove_duplicates when the value of an argument is empty
Merge branch 'feature/issue-202' of github.com:stan-dev/stan into feature/issue-202
updating model tests
Revert to displaying help when no arguments are given