Client library: eliminate compiler warnings by moving "extern" declaration into separate statement. Add conditional compilation to jerasure method module.
Test scripts: add directories to qfs test end to end test to make it work with non statically linked executables.
Cmake files: install jerasure static and dynamic libraries into proper places. Allow to override the default choice of statically or dynamically built executables by setting QFS_USE_STATIC_LIB_LINKAGE cmake variable. Cleanup all redundant libraries dependencies, and target link libraries, use cmake dependencies to generate correct link instructions, and avoid / minimize cmake code duplication. Fix dynamically executables build. Track down and fix problem with meta server layout manager global variable duplication with dynamically linked executables, resulted in unintelligible [authentication] failures due to use two different globals with the same name in different places of the the meta server executable: shared library and "main".