Package explorer with show and save and photos

Brief Description:
This is mainly concerned with extending the features of the previous package explorer where the designer was able to delete pages,add pages and preview the pages in the form of thumbnails
Success:
1.I can delete a page successfully from the project
2.I can view the project pages as small icons in the package explorer
3.I can add a page successfully to the project
Failure:
1.No one can delete a non existing page

#290 
@sshihata  @ahmadsoliman  @Malatawy15  @MennaAshraf 
please review my branch