Version 1.1.19: Fix problem when extension have similar name (ie email and mail)

This version fix a problem during the check perform during the installation of an extension in a slave site.

In the previous version, when you have on your master website two plugins in the same group having similar name like "email" and "mail", JMS may check the wrong manifest files because it find two files having the pattern "mail".

With this fix, when it find several manifest files, and additional check is added to select the one that has the expected  extension name.