stop storing items in tmp/ directory, only copy bundled ember when no over-ride present

[alexblom]

Every time Rails is initialized, ember-rails copies ember & ember-data from the local gem to tmp/ember-rails. When a user runs the ember-rails updater, versions are stored in /vendor/assets. If the user updates their ember gems instead, updated ember copies are placed in tmp/.

Changes:

1. Move the /tmp folder to a /bundled in the ember assets folder. This serves the same purpose, but means the gem only ever copies ember to one spot. (No more rake tmp:clear / updated versions in potentially 2 places)
2. Make sure there is no updated/over-ride copy of ember, and only copy the if there is none (no duplicates).

Fixes #343 & possibly issues from #345.

[tomash]

that'd help us a lot, especially given different permission systems than what's usually done with capistrano (don't ask). :+1:

[CloCkWeRX]

Oops, wrong bug/pull request.

I'm actually finding that even when I do

bundle exec rake -T I'm getting a tmp/ directory created. If I do it as the wrong user, all of a sudden I end up with an application that won't start.

I don't think that simply loading the gem should start modifying the system. +1 to this pull to stop tmp being created, but it would be better to have this as an explicit action, not an implicit one.

[alexblom]

Thanks tomash and CloCkWeRX.

I don't really use Ember Rails anymore (moved to cli around the time of this commit) - would it be useful for me to update this pr to not have conflicts?

[CloCkWeRX]

Yes please :)