SimpleConverter: Support DecimalPattern

[jornfranke]

At the moment, HadoopOffice supports defining a decimal locale for automatically recognizing datatypes in an Excel using the simple converter. In addition, it should support a Decimal pattern.

It thus should so offer the configuration option:hadoopoffice.read.simple.decimalpattern and hadoopoffice.write.simple.decimalpattern

Possible Patterns are described under the link above. Examples:

• "#,#00.0#" → 1,234.56 : This means a minimum of 2 integer digits, 1 fraction digit, and a maximum of 2 fraction digits.
• #,#00.0#;(#,#00.0#)" for negatives in parentheses.