don't overwrite variable reference when iterating

Also popuplate full backtrace when rescuing from a generic exception
to aid in debugging.
remove old commented code
implement the path_to liquid tag
new liquid global variable: editing
Merge pull request #139 from yrb/feature/consume_tag_iteration

Feature/consume tag iteration
use the latest version of the mounter (1.3.3)
Merge branch 'master' of github.com:locomotivecms/wagon
update specs for the last commit of the mounter component (34d24feeb8d5576a715e56f76e8a0db1ec17058f), referencing issue locomotivecms/wagon#140 and locomotivecms/wagon#141
Parse deploy.yml with ERB to support ENV vars
allow to pass an external lib when generating a site or list templates (useful to add new site generators)
Merge pull request #150 from kevin-cantwell/erb-parse-yml

Parse deploy.yml with ERB to support ENV vars
merge PR #150
Merge branch 'master' of github.com:locomotivecms/wagon
bump version to 1.4.0
Set exit code to 1 when something goes wrong.
Merge pull request #156 from malclocke/exit_code_1_on_failure

Set exit code to 1 when something goes wrong.
adds default page position
Merge pull request #158 from warp/fix_default_page_position

adds default page position
preparing Wagon for the desktop app version [wip]
Merge branch 'master' of github.com:locomotivecms/wagon