[#22] init user manual, refactor README.md
[#22] improve style
[#22] test image insert
[#22] change link to image
[#22] add description for invoice pages, and add glossary
[#22] correct typo and grammar
[#31] add "generate invoice" button on activity list, remove TJM from activity creation form
[#31] add modal used to fill remaining information necessary to generate invoice
change label from English to French in invoice affectation modal
[#34] begin implementation of silhouette, the project builds and application is launched
[#34] link authentication page