SE-256 MZ peaks now stored as text in metabol database

...systemsx/cisd/yeastx/db/MetabolDatabaseVersionHolder.java

.../source/java/ch/systemsx/cisd/yeastx/mzxml/IMzXmlDAO.java

...ce/java/ch/systemsx/cisd/yeastx/mzxml/MzXml2Database.java

...rce/java/ch/systemsx/cisd/yeastx/mzxml/dto/MzScanDTO.java

rtd_yeastx/source/sql/postgresql/005/schema-005.sql

...stx/source/sql/postgresql/migration/migration-004-005.sql

...t/java/ch/systemsx/cisd/yeastx/mzxml/MzXMLParserTest.java

...ava/ch/systemsx/cisd/yeastx/mzxml/MzXml2DatabaseTest.java