Fix percent function to return minimum zero

The percent function is used for ui-bars. When returning numbers below zero the bar will show up with 100% width, 'cause css don't know negative width.
Changed calculateDelta() so when unchecking a task it removes the right amount of gold and exp
chore(i18n): update locales
Add haveUnallocated string
Fixed bug when calculating the reverse delta.
Added in a case for a todo with checklists
so the gp and exp for those are reversed correctly.
Added a couple test cases for checking then unchecking tasks.
feat(halloween): add jackolantern pet
chore(github): merge pr #327
Merge branch 'brandonjreid-uncheck' into develop
chore(i18n): update locales
Fix misspelled artist's name in Rooster quest
"extrajordinary" is changed to "extrajordanary"
Issue: #4089
Merge pull request #330 from AnnaPhilips/develop

Fix misspelled artist's name in Rooster quest
fix(moment): fix deprecated warnings, use updated moment syntax
chore(moment): upgrade moment, run grunt
Merge pull request #328 from betaveros/have-unallocated

Add haveUnallocated string
add strings for Dailies tabs (Due and Grey)
remove irrelevant changes to dist/habitrpg-shared.js
Merge pull request #332 from Alys/Gaelan-hide_completed_dailies-modified

add strings for Dailies tabs (Due and Grey)
feat(item-store): unlock item-store earlier (lvl 1), see #4134
Edited capitalization for consistency

Changed capitalization of "Dailies" to be consistent
Edited capitalization for consistency

"to-do" -> "To-Do"