Remove dates from man pages

Counterpart to https://github.com/QubesOS/qubes-core-admin/pull/94

doc/vm-tools/qvm-copy-to-vm.rst

@@ -6,8 +6,6 @@ NAME
 ====
 qvm-copy-to-vm - copy specified files to specified destination VM
 
-:Date:   2012-05-30
-
 SYNOPSIS
 ========
 | qvm-copy-to-vm [--without-progress] dest_vmname file [file]+

doc/vm-tools/qvm-open-in-dvm.rst

@@ -6,8 +6,6 @@ NAME
 ====
 qvm-open-in-dvm - open a specified file in disposable VM
 
-:Date:   2012-05-30
-
 SYNOPSIS
 ========
 | qvm-open-in-dvm filename

doc/vm-tools/qvm-open-in-vm.rst

@@ -6,8 +6,6 @@ NAME
 ====
 qvm-open-in-vm - open a specified file in other VM
 
-:Date:   2012-05-30
-
 SYNOPSIS
 ========
 | qvm-open-in-vm vmname filename

doc/vm-tools/qvm-run.rst

@@ -6,8 +6,6 @@ NAME
 ====
 qvm-run - run a specified command in a specified VM
 
-:Date:   2012-05-30
-
 SYNOPSIS
 ========
 | qvm-run vmname command [aguments]