[FEATURE] Set activateContentAdapter=0 in AdditionalConfiguration

Also, introduce a concept for detecting whether or not it is okay to create or overwrite the AdditionalConfiguration.php file. If the file does not exist or the file contents matches on of the history migration files, (re)install is allowed in the EM script.
[TER] 1.0.1
[TASK] Add .editorconfig
Merge pull request #100 from coding46/patch-1

[TASK] Add .editorconfig