Replaced valuecheckMatrix() with CompareMatrices(). Updated some unit tests use Google Test.

[liangfok]

Closes #1916.

Getting this merged is a prerequisite for #1898.

[david-german-tri]

alphabetize

[liangfok]

Done.

[david-german-tri]

Added a bunch of minor comments. Obviously, many of the tests you've migrated are still in a clunky state, but I didn't pile comments onto those - this change is a huge improvement!

[liangfok]

@david-german-tri: Thanks for the thorough code review. I believe I addressed all of your comments. Can you verify the changes and merge if everything is acceptable?

[david-german-tri]

Looks like everything should be clang-formatted again

[liangfok]

@david-german-tri: I just ran clang-format and noticed it may be violating the style guide's specification on the order of includes. Here is an example change made by clang-format:

Shouldn't gtest.h be considered "other libraries' .h" meaning it should go before drake's header files?

[jwnimmer-tri]

Is the problem that you should use <gtest/gtest.h> and not "gtest/gtest.h"?

[liangfok]

The CI servers found a problem that I failed to detect due to the fact that I did not have Matlab installed on any of my local machines:

/home/ubuntu/workspace/experimental/compiler/gcc/label/linux_matlab/drake/systems/plants/test/compareParsersmex.cpp: In function ‘void mexFunction(int, mxArray**, int, const mxArray**)’:
/home/ubuntu/workspace/experimental/compiler/gcc/label/linux_matlab/drake/systems/plants/test/compareParsersmex.cpp:104:64: error: ‘valuecheckMatrix’ was not declared in this scope
       valuecheckMatrix(matlab_H, cpp_H, 1e-8, "H doesn't match");
                                                                ^
/home/ubuntu/workspace/experimental/compiler/gcc/label/linux_matlab/drake/systems/plants/test/compareParsersmex.cpp:116:55: error: ‘valuecheckMatrix’ was not declared in this scope
                        "joint_limit_min doesn't match");
                                                       ^
/home/ubuntu/workspace/experimental/compiler/gcc/label/linux_matlab/drake/systems/plants/test/compareParsersmex.cpp:125:70: error: ‘valuecheckMatrix’ was not declared in this scope
       valuecheckMatrix(matlab_phi, cpp_phi, 1e-8, "phi doesn't match");
                                                                      ^

[jwnimmer-tri]

Here's a final suggestion, taken from the changelog -- for any users who consult this PR for advice:

Unit tests that originally contained

    valuecheckMatrix(matrix1, matrix2, tolerance);

should be modified to use Google Test and the following line:

    EXPECT_TRUE(drake::util::CompareMatrices(matrix1, matrix2, tolerance, MatrixCompareType::absolute));