Merge tag 'v2.3.0'

v2.3.0
Fix windows spawn
Merge pull request #109 from strongloop/feature/fix-windows-spawn

Fix windows spawn
Upgrade to loopback-workspace 2.4.0
Merge pull request #112 from strongloop/feature/lb-workspace-2.4.0

Upgrade to loopback-workspace 2.4.0
Simplify success message.

Removed the unnecessary step of telling users they have to create an
account with a matching email.

Also through in a link to the dashboard after the prompt to go there.
slc update command

npm install -g will install peerDependencies, if they don't exist, but
it won't update them, it only complains about them. Add an slc update
command to update strong-cli and its dependencies. It will fail and dump
error if at the end, their are peerDependency problems. Unfortunately,
due to a mis-design of npm, any globally installed module with a problem
will cause strong-cli to appear to have a dependency problem, but we
can't help that.
Fix usage in README, --help not -help
Merge pull request #113 from strongloop/feature/update-command

slc update command
v2.4.0
Merge branch 'release/2.4.0' into production