Simplify database initialization, fix default data

Summary:
Some users have had problems with the database initialization process, simplify
it by creating a new "initialize.sql" dump at v34.

I also populated this dump with the right landing screen (so all the tools
actually have links) and a default avatar.

Test Plan:
Dropped all databases, initialized according to documentation, ended up in a
good state with sensible defaults.

Reviewed By: jungejason
Reviewers: aran, jungejason, tuomaspelkonen
CC: aran, jungejason
Differential Revision: 210