tracing ability added into zrt test suite, zrt api extended by trace related feauture
efficient lazymount implemnetation, comments added for path_utils
support for _SC_AVPHYS_PAGES and tests added
bug fixed: open O_TRUNC,O_WRONLY,O_RDWR for dirs must be not allowed
tests fixed to be PASSED during tracing
fixed issue #131, nvram tests updated
issue #128, minor changes in tests, also added test for testing filesystem from constructor function
docs updated: info about gcov, trace was added