Allow updating of boolean/integer attributes to 0.

The original change that caused this issue is 08dcd1d868083a0bc0be28a1b1312bdbe32f95b6.
Since integer 0 and string '0' both are considered 'empty', it is impossible to
set boolean flags to zero, such as setting visibility to '0'.
Merge pull request #5 from adamfranco/Update_visibility_to_0

Allow updating of boolean/integer attributes to 0.
installed test version for Moodle 2.4
trouble in moodle 2.4 when courses are not in a category
typo in function get_module_grades get_coursemodule_from_instance should be get_coursemodule_from_id
Merge branch 'master' of github.com:patrickpollet/moodlews
get_my_courses broken with Moodle 2.4.3 when not admin see https://moodle.org/mod/forum/discuss.php?d=226161 + some troubles when Moodle is in full debug mode with display_errors on
Merge branch 'master' of github.com:patrickpollet/moodlews
operation get_modules_grade fixed in M 2.4
fixed all php strict standard notices
better fix to get_my_courses by removing only extrafields that are gone in Moodle 2.3
Update README
Update README
Update README
 inversion of users/group-cohort parameters in affect_users_to_xxx or remove_users_from_xxx Thanks to Matthieu.Marc@ensam.eu
 inversion of users/group-cohort parameters in affect_users_to_xxx or remove_users_from_xxx Thanks to Matthieu.Marc@ensam.eu
oups broke fix for PHP sctrict notices in latest commit