Use upstream passwd-user

Fork no longer needed now that sindresorhus/passwd-user#2 has been
merged and published (as 1.0.0).
v0.1.9
Merge branch 'release/0.1.9' into production
Merge tag 'v0.1.9'

v0.1.9

 * Use upstream passwd-user (Ryan Graham)

 * pm: exit on loss of parent IPC channel (Sam Roberts)

 * package: sync package name with README (Sam Roberts)

 * test: rewrite comments referring to strong-deploy (Sam Roberts)

 * pm-install: strong-deploy is now called strong-pm (Sam Roberts)

 * deploy: Add tarball over HTTP deploy support (Krishna Raman)