Testing written for some trig and other basic functions
added tests for 'log' function
added test for 'sqrt' function
added testing for 'tan' function
Added tests for inverse hyperbolic trig functions
Added testing for various functions including log and pow
Merge branch 'develop' into feature/agrad/rev-tests

Conflicts:
	src/stan/agrad/rev/as_bool.hpp
When dimensions don't match, print out the variable name involved as well.
fixed dump sign issue as suggested by ksvanhorn in issue #197
removed tabs; indented files using emacs
updated boundary test for test/agrad/rev/acos
updated boundary test for test/agrad/rev/acosh
changing behavior of functions to pass through to the underlying library calls where reasonable. updated tests to show behavior.
Merge pull request #2 from stan-dev/jadams41-agrad/rev-tests

Updating code and tests.
Unify the format of the write_error_msg text during initialization and sampling.
Merge branch 'develop' into feature/agrad-rev-tests

Conflicts:
	src/test/agrad/rev/abs_test.cpp
	src/test/io/dump_test.cpp
changing uses of std::isinf (C++-11 feature) to boost::math::isinf, making sure test-headers pass
Merge branch 'develop' into feature/agrad-rev-tests
Merge pull request #213 from stan-dev/feature/unify_write_error_msg

Unify the format of the write_error_msg
Merge pull request #370 from stan-dev/feature/agrad-rev-tests

Adding some more agrad rev tests.