Postgres 9.1 dependencies

[scurvy]

The readme states that Postgres 9.0 or later is required. Actually, Postgres 9.1 or later is required as one of the rake setup tasks creates an unlogged table. Unlogged tables are only available in 9.1 and later.

rake aborted!
An error has occurred, this and all later migrations canceled:

PG::Error: ERROR:  syntax error at or near "UNLOGGED"
LINE 1:       CREATE UNLOGGED TABLE blames (
                     ^
:       CREATE UNLOGGED TABLE blames (
        id SERIAL PRIMARY KEY,
        repository_hash CHARACTER(40) NOT NULL,
        revision CHARACTER(40) NOT NULL,
        file CHARACTER VARYING(255) NOT NULL CHECK (CHAR_LENGTH(file) > 0),
        line INTEGER NOT NULL CHECK (line > 0),
        blamed_revision CHARACTER VARYING(40) NOT NULL,
        updated_at TIMESTAMP WITHOUT TIME ZONE
      )