Fix signed to unsigned comparision warning.
Merge pull request #238 from shehzan10/devel

Added warning messages for when submodules are not cloned
Merge pull request #239 from bkloppenborg/devel

Fix signed to unsigned comparison compiler warning.
BUG: Fixed issues with atan2 in CUDA and OpenCL backends

- This should fix issue #236
Merge pull request #240 from pavanky/atan2

BUG: Fixed issues with atan2 in CUDA and OpenCL backends
TEST: Adding global reduction tests
Changing af::af_cfloat to af::cfloat for C++ API
Properly catching and returning errors from af_sort*
TESTS: Adding tests for math functions
TEST: Adding tests for binary functions
Merge pull request #241 from pavanky/test

Addding tests for reductions and element wise operatons
FEAT: Adding support for hypot
TEST: Adding tests for complex binary functions
Merge pull request #242 from pavanky/hypot

FEAT: Adding support for hypot
BUG: Fixed problem in cast for OpenCL backend
BUG: Fixed a problem when casting complex numbers
Merge pull request #244 from pavanky/jit_fixes

Jit fixes
BUGFIX Fixed memory leak in image io, performance improvements