Merge pull request #1047 from boegel/fix_path_to_top_of_module_tree

fix path_to_top_of_module_tree to consider multiple paths to the top of the module tree
fix HierarchicalMNS for cgoolf and goolfc toolchains
add definition of iompi toolchain
clean up code in HierarchicalMNS.det_toolchain_compilers_name_version
fix remarks
fix minor remark
fix indent
Merge pull request #1049 from boegel/hmns_goolfc_cgoolf

fix HierarchicalMNS for cgoolf and goolfc toolchains + add iompi definition
Merge pull request #1048 from boegel/v1.15.x

bump version to v1.15.1, update release notes
fix unit tests broken due to shellshock patch
fix case where testing is not enabled in modulestool.py tests
fix long line
fix broken test that verifies mismatch on 'module' function
add definition of gimpi toolchain
move gimpi toolchain definition to correct location
fix blatently wrong code in path_to_top_of_module_tree function
enhance unit test to catch missed bug
fix $MODULEPATH extensions for Clang/CUDA, include versionsuffix in module subdir
fix tiny remark
fix broken test