Adding first rudimentary version of tagging and filtering. New users get three tags: morning, afternoon and evening. At the moment, one can not change these tags or add new ones. There are also some problems: tagging a newly added task, also tags one of the existing tasks. Also, when having an active filter and removing the corresponding tag from a task, that task is immediately hidden, although you are still editing it.
Merge branch 'develop' into toebu-tags-filters

Conflicts:
	src/app/index.coffee
	src/app/tasks.coffee
	styles/app/index.styl
	views/app/index.html
	views/app/tasks.html
rename user._tagFilters to user.filters
for now don't live-bind to {#each _user.tags}. There's a derby bug
here, so we'll have to refresh when users add new tags until we get
that fixed
add new tag
add tag-editing context (add new, delete). still have to refresh after everything, do to the live-bound each bug
cap minimum %chance of drop to 1% so users still rewarded for
championed habits. Will remove once we have streaks / combos. Also
factor in task difficulty
nix the "remove if empty auth & no more session" cron task
Merge branch 'develop'
add bs-docs-masthead
Merge pull request #779 from Shaners/develop

Rename the Sprinkle Button to Pour
Merge branch 'develop'
Merge pull request #784 from Shaners/develop

Fix to some pixel grid alignment issues
Merge branch 'develop'
don't deduct GP unless purchase successful (see #233)
Merge branch 'develop'
rename _view.* to _* - don't know why I did that whole _view.* thing
in the first place, but whatevs
move task-corruption cleanup to cron, restore missing tasks to list -
let's see if this fixes #777
Merge branch 'develop'
fix to previous commit