new module: detail sales
new module: create and read purchase

note:
- storeId config is useless so I dumped it
- field-stock-amount base can be negative by default
- remove frame on maximized window

new custom base:
- combo-stock-variant
finished adding: purchase crud module

new module:
- edit purchase
- search purchase
new module: detail purchase
fix bugs: F1 conflict

fix bugs:
- check sales and purchase edit processing algorithm
- minor
favicon added

new:
- unlimited stock
new module: notification

- notification with push feature for real-time update from server

fix bug:
- F1 and F2 now can only trigger action after user login to app
Merge pull request #4 from nicklaros/development

new module: notification