Merge pull request #208 from Useful-Innovation/changes

Link to offert now has an icon
removed unwanted files
Merge pull request #210 from Useful-Innovation/johans-fixes

removed unwanted files
Merge pull request #211 from Useful-Innovation/changes

Changes
Changed layout on create_invoice

*You can now see the diff between the offered price and the total price
for work and the diff between offered price and the total price.
*added a function to calculate the total in-price of a purchase
*added a function to calculate the total price for the hours worked