Add compiler --list options

[cgewecke]

(This goes with some changes at truffle-compile 63)

• Adds --list option to compile command & tests

Options

truffle compile --list                   # Recent stable releases from solc-bin (JS)
truffle compile --list prereleases       # Recent prereleases from solc-bin (JS)
truffle compile --list docker            # Recent docker tags from hub.docker.com
truffle compile --list releases --all    # Complete list of stable releases.

Output

truffle compile --list
[
 "0.4.23",
 "0.4.22",
 "0.4.21",
 "0.4.20",
 "0.4.19",
 "0.4.18",
 "0.4.17",
 "0.4.16",
 "0.4.15",
 "0.4.14",
 ".. and 31 more. Use `--all` to see full list."
]

Help

truffle compile --list --help

See available solc versions. (Default: solcjs stable releases)

USAGE:
   --list [option] [--all]

OPTIONS:
 `docker`         recently published docker tags
 `releases`       solcjs stable releases
 `prereleases`    solcjs nightly builds
 `latestRelease`  solcjs latest