clean up tests to use FactCheck

[davidlizeng]

Reorganized test.jl and test2.jl into affine, lp, and socp test files as per #42 .
All tests also now use the FactCheck package.

[coveralls]

Coverage decreased (-0.09%) when pulling 077e892 on clean_tests into 5171206 on master.

[karanveerm]

Few issues:

• This will always pass travis because of the exit status. Read: https://github.com/JuliaLang/FactCheck.jl#exit-status and fix.
• It's preferable to have test_lp separate, so we can test other LP solvers on it as well.

[coveralls]

Coverage increased (+6.89%) when pulling ca24f9f on clean_tests into 5171206 on master.

[coveralls]

Coverage decreased (-47.93%) when pulling d8fd557 on clean_tests into 5171206 on master.

[coveralls]

Coverage increased (+12.94%) when pulling 196040b on clean_tests into 5171206 on master.

[karanveerm]

@davidlizeng I think this is ready to merge into master. Coverage should go up another 20% after we test with SCS on travis, after which most of the uncovered lines are error checks, etc. of lower priority.

[mlubin]

This is usually listed in test/REQUIRE since it's only needed to run tests.

[karanveerm]

What would be the nicest way for FactCheck to still be present for travis?
JuMP seems to be doing this: https://github.com/JuliaOpt/JuMP.jl/blob/master/.travis.yml#L11

[mlubin]

Oops, I guess we never tidied that up. @IainNZ
If you just use Pkg.test("Convex", coverage=true) then first the testing dependencies will be installed and then test/runtests.jl will be run. That's the "right" way to do it.

[karanveerm]

Done, thanks! I'm going to keep this PR open for another few days to see if anyone has other feedback, and merge it then.

[coveralls]

Coverage increased (+17.61%) when pulling b8de06e on clean_tests into 5171206 on master.