PACKAGERS BEWARE: Build changes required

I've just committed a couple of patches that change the requirements
for building pgAdmin for packages:

- You will need node.js and yarn to be installed for building

- During the build process, do something like this:

cd $PGADMIN_SRC/web
yarn install
yarn run bundle

This will create web/node_modules and pgadmin/static/js/generated
directories that will need to be included in packages.

This is part of a numer of in-progress changes:

1) To remove all vendor code from the pgAdmin source tree. Eventually
is should all be installed using Yarn into a vendor/ directory. Each
developer/packager will need to do this.

2) Web-packing of all the JS and CSS code. This will minimise all the
JS/CSS to reduce file transfer sizes, and bundle it together into as
few files as possible to minimise client/server round trips.

3) A move towards React to improve UI rendering/generation etc.

--
Dave Page
Blog: http://pgsnake.blogspot.com
Twitter: @pgsnake

EnterpriseDB UK: http://www.enterprisedb.com
The Enterprise PostgreSQL Company