Fixed spelling error in Database.java

Changed error message "Error occured while trying to connect to the database" to "Error occurred while trying to connect to the database"
Merge pull request #832 from levyj/master

CLEANUP: Fixed spelling error in Database.java
[PDI-9289] Meta-injection enabled for Excel Writer output fields.
Merge pull request #870 from gretchiemoran/master

[PDI-9289] Meta-injection enabled for Excel Writer output fields.
PDI-12893 - JUnit test.
PDI-12893 - Exception in thread "main" java.util.ConcurrentModificationException