Nxt-simplecost

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- add french translation
- update forms for Django 1.11
- update export pdf
- add update and delete functions to expense in expense's list
- add ajax function to filter the list of expenses with all, a monthly range or the actual quarter range
- modify export pdf to support same filter as the expenses list's views

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- first commit
- add expenses list view
- add ajax function to list all expenses
- add a view to generate a pdf file with all expenses