Convert unit tests from Boost Test to Google Test
update tests to address warnings, most of which were signed/unsigned or int/float comparisons
malformed test in GDALUtilsTest
gtest unsigned comparison cleanups
Merge pull request #644 from PDAL/convert-boost-test-to-google-test

Convert unit tests from Boost Test to Google Test
Port Stats filter
Merge pull request #646 from PDAL/move-stats-filter

Port Stats filter
Move Crop filter
Merge pull request #647 from PDAL/move-crop-filter

Move Crop filter
fix the crop filter tests
help find plugins in build location
add_test needs WORKING_DIRECTORY set on linux
CropFilter should be built with or without GEOS
remove comments, WITH_GEOS has no meaning anymore
Merge pull request #648 from PDAL/clean-up-crop

Clean up crop
make the crop filter a builtin filter once again
_VARIADIC_MAX must be increased on msvc for gtest
Merge pull request #651 from PDAL/gtest-fix-msvc

_VARIADIC_MAX must be increased on msvc for gtest
Merge pull request #650 from PDAL/make-crop-builtin-filter

make the crop filter a builtin filter once again
Use OPTIONAL_COMPONENT_SWITCH for attribute plugin

Best to test with and without on Travis.