minor refactoring for class constant in users (ROLES)
added specs that ensure adequate removing and validations of websites
major commit:
    implemented directory removal after website.destroy
    implemented folder uniqueness validation before create
    revealed error in folder name assignment, since filename of zip can
    be inconsistent with content
    edited README according to changes
typos in README
Merge branch 'develop'
merged README
Conflicts:
	README.md