Add validation for SiteLogBuffer value

make sure, it is set to 1 or larger
Add validation for SiteLogBuffer value 

make sure, SiteLogBuffer is populated with a valid value
Add validation for SiteLogBuffer value 

new Validation resourcekey
Add validation for SiteLogBuffer value 

fix resource key name
Merge pull request #189 from sleupold/patch-9

DNN-6065:  Add validation for SiteLogBuffer value