Create the folder
%SystemDrive%\ProgramData\Microsoft\SQL Server Management Studio\12.0\Addins\
if it does not exist. Then just copy the file from:
%SystemDrive%\ProgramData\Microsoft\SQL Server Management Studio\11.0\Addins\PoorMansTSqlFormatterSSMSAddIn.AddIn
to
%SystemDrive%\ProgramData\Microsoft\SQL Server Management Studio\12.0\Addins\PoorMansTSqlFormatterSSMSAddIn.AddIn