log_manager.cc:
Log manager handles cases where there are mismatch in user privileges.
Mark log files enabled in the global lm_enabled_logfiles_bitmask after initialization so that it reflects reality in error cases. In general, take into account the possibility that any phase in initialization may fail and read return values.
Replaced file_exists_and_is_writable to check_file_and_path which has a slightly different logic and which detects if file open fails for a few different reasons.
Improved logging (in stderr) in general in error cases.
gateway.c: Also check home directory accessibility in case when it is provided as a command-line argument. Added function check_dir_access to provide that function. Read return value of skysql_logmanager_init and exit (nicely) if it failed.
skygw_utils.cc: initialize mlist with version number 2, which indicates that object is initialized (different than zero) and that there are no active updates on the object (version%2==0).
Client flags are now copied to each backend and used in their connections.
log_manager.cc: fixed string allocation where one byte was missing.
mysql_client.c: fixed string allocation where one byte was missing.
mysql_client.c, added functions create_auth_fail_str, and get_username_from_auth to implement creation of similar error msg with MySQL. There is one difference left, because MaxScale prints IP address instead of hostname in error message.
Also changed 'authorization failed' to 'access denied'
mysql_common.c: fixed memory leak in gw_receive_backend_auth, and replaced error code '2800' with '28000'.
readconnroute.c:handleError didn't set *succp pointer so uninitialized value was used in caller's context.
makefile.inc: added -lm to linker flags
mysql_backend.c: added a few comments
If .secrets file is not used it means that encrypted password is not used. Moved log entry away from error log and placed it to message log. It still prints it multiple times though.
