Fix for #2175 - Spacebars block comment cause unexpected errors

This fixes an edge case where a comment is followed immediately
by an {{else}} token.
Merge pull request #2180 from arbesfeld/comments-fix

Fix for #2175 - Spacebars block comment causes unexpected errors
Fix #2157 (issues with `=` in template args)
Add _nestInCurrentComputation flag to UI.render.

Internally, Blaze sometimes relies on `UI.render`'s autoruns nesting
within the current computation, but it's often the case that callers
don't want `UI.render`'s autoruns to be stopped when the outer
computation is invalidated. This change fixes a bug in {{#each}}: if
`addedAt` ran inside a `Deps.autorun`, and then the outer computation
was invalidated, the corresponding item would stop updating because the
autoruns set up by `UI.render` would be stopped.

Fixes #2156.
Use Meteor.absoluteUrl() to redirect in force-ssl
Expose underscored animation hooks and add a test
Update an accounts-ui-unstyled comment
Show name of logged-in user after email verification/password reset