Previously a user of the phar distribution would have to invoke psalm as
`vendor/bin/psalm.phar`. This is different to the command given in
the psalm documentation, `vendor/bin/psalm`
I also copied all files from the psalm/phar repo into
assets/psalm-phar, so that development can be concentrated in this repo.
The travis-deploy-phar.sh should copy any changes made back into the
psalm/phar.git repo.
