No single quotes in media file insert url on mediaFileAdd!save.rol

[gregh3269]

This one should go into 6.1.x branch too.

[snoopdave]

Manually tested on the 6.1.7 integration build (roller-6.1.x plus #198, #199, #200, #205 and #207), with Tomcat 9, JDK 11 and MySQL 8.

• "Create weblog entry" from an image and from a PDF inserts href="…" and src="…" with double quotes.
• A file name containing ' produces a working link and image.
• The thumbnail shows on the published entry.

Result: pass.