add basic pld linux support

PLD Linux Distribution: https://www.pld-linux.org/
Merge pull request #1490 from glensc/pld-distro

add basic pld linux support
Update CHANGELOG
v1.1.3
Default forward port adapter for VirtualBox should be 1
v1.1.4
Up version for development
Proper error message if invalid provisioner is used [GH-1515]
Better detect SSh connections closing
Don't error if machine shuts down really quickly on graceful [GH-1505]
Error message if private key not owned by right user [GH-1503]
Don't load plugins.json plugins in Bundler env
Better plugin dev experience through warnings
More comprehensive synced folder validation [GH-1499]
Don't error too early when config.vm.box is not properly set
Human friendly error on exit code 126 from VBoxManage
better comments on the last change
Properly detect in valid provisioners
Allow disabling prepend/append hooks
Only prepend/append once for hooks