Split out ghc78 installation into its own role

Signed-off-by: Ricky Elrod <ricky@elrod.me>
Split nginx out to its own role, too

Signed-off-by: Ricky Elrod <ricky@elrod.me>
Move ghc-path.sh over to new role

Signed-off-by: Ricky Elrod <ricky@elrod.me>
Move nginx.list over to new nginx role

Signed-off-by: Ricky Elrod <ricky@elrod.me>
Let roles configure their own nginx.

Signed-off-by: Ricky Elrod <ricky@elrod.me>
First go at Tryhaskell (nginx config needs tweaks)

Signed-off-by: Ricky Elrod <ricky@elrod.me>
gitignore inventory, sigh

Signed-off-by: Ricky Elrod <ricky@elrod.me>
First go at tryhaskell

Summary:
- tryhaskell role
- move ghc78 out to a role
- move nginx out to a role
- update hl role to not do this stuff
- update hl deploy playbook to make use of new roles
- tryhaskell playbook
- nuke inventory since we hide IPs now (sigh)
- add inventory to .gitignore
- suck at using Phabricator properly, and do all of these in one review.

Test Plan: Deployed tryhaskell (made use of the new roles)

Reviewers: austin

Differential Revision: https://phabricator.haskell.org/D415