Perf dashboard should have a script to setup database

Perf dashboard should have a script to setup database
https://bugs.webkit.org/show_bug.cgi?id=153906

Reviewed by Chris Dumez.

Added tools/setup-database.py to setup the database. It retrieves the database name, username, password
and initializes a database at the specified location.

* Install.md: Updated instruction to setup postgres to use setup-database.py.
* tools/setup-database.py: Added.
(main):
(load_database_config):
(determine_psql_dir):
(start_or_stop_database):
(execute_psql_command):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@196190 268f45cc-cd09-0410-ab3c-d52691b4dbfc