[PDI-12565]LIKE pattern matching of meta

When querying tables and columns in Thin JDBC meta, use SQL-LIKE pattern matching.
'_' wildcards a single character.
'%' wildcards any number of characters.

Pattern is converted to a regular expression. All regex characters in pattern are escaped before matching.

http://jira.pentaho.com/browse/PDI-12565
[PDI-12565]ThinJDBC getString is row type agnostic

getString should always returns String if value is set, casting value to string
null is returned if column value is not set

http://jira.pentaho.com/browse/PDI-12565
Merge pull request #649 from hudak/PDI-12565

[PDI-12565] LIKE pattern matching of meta