Resolve "Profile endless loading"

Closes #90 (closed)

ProfileService.getStudent() caches student data in order to prevent api calls. This method used Promise.resolve() to return a promise when data has been already cached.

...
if (sessionStudent != null) {
            return Promise.resolve(JSON.parse(sessionStudent
...

This operation may cause problems in some components (like bootstrap modal window which used by LoadingService)

Promise.resolve() was replaced by new Promise(resolve, reject) in order to solve such problems

       if (sessionStudent != null) {
            return new Promise((resolve, reject) => {
                try {
...