Ignore exit codes from "npm list --json" as they can be misleading

Instead just try and parse the JSON on stdout.  If the command doesn't
produce JSON fail, then the error handler still exists.  Bugs in npm or
packaging like https://bugzilla.redhat.com/show_bug.cgi?id=986422 can
cause package lists to come back empty even if the error's harmless.
Merge pull request #56 from domcleal/ignore-exitcode

Ignore exit codes from "npm list --json" as they can be misleading
Set $HOME for npm commands.
Added logic to only set $HOME on puppet 3+.
Merge pull request #59 from myplanetdigital-experimental/59-npm-set-HOME

Set $HOME for npm execs (pkgs like node-gym require)
Changed Amazon package name
Merge pull request #61 from davideme/master

Changed Amazon package name
Update init.pp

Was including the development (unstable) even when flag was false.
#pr-62 hasn't been merged yet... so...
add support for Scientific Linux operatingsystem
Merge pull request #65 from ccin2p3/scientific_linux

add support for Scientific Linux operatingsystem
Fix for chrislea ppa that already installs npm
Merge pull request #68 from barthoda/master

Ubuntu uses uppercase for the operatingsystem fact
Merge pull request #64 from vpassapera/patch-1

Fix ubuntu development package being installed when dev flag is set to false
Prepare a 0.5.0 release.
Merge pull request #73 from apenney/050-release

Prepare a 0.5.0 release.
Remove metadata, since it's not correct
Merge pull request #74 from hunner/remove_os_stuff

Remove metadata, since it's not correct
Fix the specs.
Update travis settings.
Merge pull request #76 from apenney/fix-specs

Fix the specs.