ALLJOYN-1947 unordered_map include in STLContainer.h needs to be platform
specific for darwin

unordered maps are a part of C++11 standards and STLContainer.h contained
a generic include which caused build errors for darwin since in darwin
the header file for unordered_map is under <tr1/unordered_map>

Change-Id: Ib6846b5e923fc3afed442c576afef2d109fd85be
ALLJOYN-1944 Fix memory leak in String::operator[]

Change-Id: I847253ea4dabd9bdfdb5491df4627d57d6a342e7