* Remove unneeded package.json fields from dist
We don't need dependencies and devDependencies in the package.json within the Yarn distributable, as the dependencies are bundled with Yarn itself. We also don't need "scripts" or "jest" as they're purely for development
* Add script for publishing to npm
* Add Jenkins job for publishing to npm
Instead of including all the raw JS files in the dist tarball, just use the single Yarn JS file that's built as part of the build, along with a few other files that are required. This significantly reduces the number of files in the tarball:
```
C:\src\yarn\dist (bundle-as-dist) (yarn@0.23.0-0)
λ find .
.
./bin
./bin/node-gyp-bin
./bin/node-gyp-bin/node-gyp
./bin/node-gyp-bin/node-gyp.cmd
./bin/yarn
./bin/yarn.cmd
./bin/yarn.js
./bin/yarnpkg
./bin/yarnpkg.cmd
./lib
./lib/v8-compile-cache.js
./lib/yarn-cli.js
./LICENSE
./package.json
```
There are three .js files in the archive:
- `lib/v8-compile-cache.js`: Speeds up instantiation time by using the V8 code cache (https://www.npmjs.com/package/v8-compile-cache). This needs to be separate as it has to load **before** the bulk of the application code is loaded, so it can **not** be bundled
- `lib/yarn-cli.js`: Contains all the bundled Yarn code
- `bin/yarn.js`: Entry point to the app, just like today. Loads `v8-compile-cache` then loads `yarn-cli`
This change means that **only** the JavaScript files that are actually used are included, resulting in a nice file size reduction for the installation packages:
Differences are due to differing compression algorithms: Debian packages use xz or LZMA, RedHat uses gzip, Windows installer uses Cabinet
They're also slightly faster to extract:
Testing was performed on my desktop computer (Intel Core i5 6500, Samsung 850 Evo 1TB SSD, Windows 10), with testing for Linux stuff (like installing the Debian package) tested in a Docker container.
Raw data: https://docs.google.com/spreadsheets/d/1d8jdf3DU_GUFdotlPl08PkYa8SkzStK2tgnQ54ivsm0/edit?usp=sharing
Performance is very slightly faster when using `v8-compile-cache` along with the bundled file, but it's not extremely significant (`yarn --version` went from 0.19s to 0.14s on my BuyVM server). The difference might be bigger on servers with slower disks (HDD) or with more overloaded servers.
I also deleted the `build-dist.ps1` file because we _should_ be able to assume that Bash is available on Windows, particularly if Git is installed (as it comes with Git Bash). I need to verify that this works on AppVeyor.
