BS-2072

Add 2 steps in the pattern expression migration :
- Before parsing content, remove the "&nbsp;" by whitespace to remove the # character that appeared in the message of email connector
- If a dependencies recognized in the message, if it already has the ${} around it, not added a second time.

Conflicts:
	bundles/plugins/org.bonitasoft.studio.migration/src/org/bonitasoft/studio/migration/custom/migration/expression/PatternExpressionMigration.java