test/test: fix sha of test user
endpoints_test: add tests for user change password
test: use a constant username instead of having everyone rewrite it
model/entry: use tag separator when joining entries
model/entry: create a function to parse tags
model/entry: move get entries function from model/user
model/entry_test: add a test for get entries
model/user_test: add tests for user entry related functions
test/test: set the default password of the test user