Steem-in-a-box v2.1.0 Release

 - Added `example.env` file, showing various .env options that can be configured

- Added `STEEM_SOURCE` build argument to `dkr/Dockerfile` and `dkr_full/Dockerfile` - this allows for
   the default Git repository to be changed if needed, e.g. building forks / testing changes made on personal fork

**Changes to run.sh**

 - Now uses [Privex ShellCore](https://github.com/Privex/shell-core), so I don't have to keep copy-pasting
   code snippets into the project.

- Added `STEEM_SOURCE` env var which can be overrided using `export STEEM_SOURCE=xxx` or by adding the
   config option to `.env`

- `build()` supports STEEM_SOURCE as both a build arg, and env fallback.
    - First checks if `STEEM_SOURCE` was specified in the CLI build arguments
    - If it was specified in the CLI build arguments, then that takes precedence and the env var `STEEM_SOURCE` will be ignored.
    - If it WASN'T specified in the build arguments, it will add a build argument for STEEM_SOURCE using the env var `STEEM_SOURCE`

- The env option `PORTS` now supports the more specific `1.2.3.4:8090:8090` format, allowing for exposing ports only on localhost,
   or only for a specific external IP address etc.

small typo fix

formatting improvements

much better README

v0.19.0rc2

bump to v0.18.2

bump to v0.18.1

bump to hf18

HF17

Merge pull request #3 from williambanks/master

Updated with /shm/ directory, and bump to v0.16.3