Fail on empty name

Trying to install a package with an empty name globally leads to
removing all global node modules.
lru-cache@2.3.0
tar@0.1.17
node-gyp@0.9.3
node-gyp@0.9.4
node-gyp@0.9.5
v1.2.16
cmd-shim@1.1.0
v1.2.17
remove cmd-shim util

Forgot to do this earlier.  It's not used any more, the standalone
package is.
Update documentation to reflect the commands used when opening a browser
request@2.16.6
npm-registry-client@0.2.20
v1.2.18
build: Link mans properly

Fix #109 (again, apparently?)
read-package-json@0.4.0
doc: Add and differentiate unix/win node version managers
remove exec.js, use child_process.execFile

Fixes #3312
fs WriteStream has destroy(), not close()
replace `./lib/utils/sha.js` with `sha`

closes #3381