Change licenses for ScanSnap Manager casks

Fujitsu offers a free download of the software and permits free usage on one
machine at a time. The homebrew-cask `:commercial` stanza should be used for
software, which is not freely available, as per
https://github.com/caskroom/homebrew-cask/blob/master/doc/CASK_LANGUAGE_REFERENCE.md#license-stanza-details.
Therefor, `:gratis` should be a better fit.

Casks/scansnap-manager-s1300.rb

@@ -5,7 +5,7 @@ cask :v1 => 'scansnap-manager-s1300' do
   url 'http://www.fujitsu.com/downloads/IMAGE/driver/ss/mgr/m-s1300/ScanSnap.dmg'
   name 'ScanSnap Manager for Fujitsu ScanSnap S1300'
   homepage 'http://www.fujitsu.com/global/support/computing/peripheral/scanners/software/s1300m-setup.html'
-  license :commercial
+  license :gratis
 
   pkg 'Scansnap Manager.pkg'
   

Casks/scansnap-manager-s300m-s500m-s510m-fi-5110eoxm-legacy.rb

@@ -8,7 +8,7 @@ cask :v1 => 'scansnap-manager-s300m-s500m-s510m-fi-5110eoxm-legacy' do
   name 'ScanSnap Manager for Fujitsu ScanSnap S510M'
   name 'ScanSnap Manager for Fujitsu ScanSnap fi-5110EOXM'
   homepage 'http://www.fujitsu.com/global/support/computing/peripheral/scanners/software/mac.html'
-  license :commercial
+  license :gratis
 
   pkg 'ScanSnap_V22L11.pkg'
 

Casks/scansnap-manager-s300m-s510m.rb

@@ -6,7 +6,7 @@ cask :v1 => 'scansnap-manager-s300m-s510m' do
   name 'ScanSnap Manager for Fujitsu ScanSnap S300M'
   name 'ScanSnap Manager for Fujitsu ScanSnap S510M'
   homepage 'http://www.fujitsu.com/global/support/computing/peripheral/scanners/software/mac-mg22-eol.html'
-  license :commercial
+  license :gratis
 
   pkg 'ScanSnap_V22L16.pkg'
 

Casks/scansnap-manager-sv600.rb

@@ -5,7 +5,7 @@ cask :v1 => 'scansnap-manager-sv600' do
   url "https://www.fujitsu.com/downloads/IMAGE/driver/ss/mgr/m-sv600/MacScanSnapV#{version.gsub('.','')}WW.dmg"
   name "ScanSnap Manager for Fujitsu ScanSnap SV600"
   homepage 'http://www.fujitsu.com/global/support/computing/peripheral/scanners/software/'
-  license :commercial
+  license :gratis
 
   pkg 'ScanSnap Manager.pkg'