Back out wrong index attempt; #449
Start building tables; #449
Start adding tipping UI for brands; #449
Store companies in `participants`; #449

Rather than having a separate `companies` table, we can just the
participants table for both companies and people. That's why it's named
participants in the first place, instead of users or humans or some
such.
Back out ill-advised changes to Participant; #449

We're going to greatly simplify the schema changes for this feature. I
had started modifying set_tip_to for the more complicated schema, and it
made the test suite reeeeeaaallly borked. Backing this out fixes the
test suite and I'll commit the new schema changes next.
Greatly simplify schema for #449

I had originally thought we would have new tables for `companies` and
`brands` but we're going to use the existing `participants` table.
Instead, this adds a `type` column to `participants` which is an ENUM
with three values: individual, group, and open group. Individuals will
behave as participants currently do. Groups will say "We are" instead of
"I am" but will otherwise be the same. Open groups will be where we go
into all of the voting to decide how to split up the money.
Start folding /for/%brand into /%username

Now that we're using participants to represent both individuals and open
groups, we don't need a separate namespace for brands.
Back out changes to js side of tipping; #449

I backed out the server-side changes to tipping in 579933e6ffc.
Merge branch 'master' into for

Conflicts:
	branch.sql
Gotta represent. #449, #657

I'm changing the 'open group' to 'open company'.
Fold /for/%brand into /%username; #449
Rough in UI for identifications; #449
UI for open groups is MVP; #449

Trusted users can answer the question "Who is Gittip?" and we compute a
percentage split for the pot based on those answers. The rest is
details. Or faucets and fixtures. ;-)