Modified netcdf-converter

Modified Converters classes to implement the IConverter interface and modified to don't run like a static classes.
Added ConverterServlet

Added ConverterServlet and modified pom to manage new dependencies. Fixed problems with the version of compiler in netcdf-converter pom.xml file.
Created NCGlobalAttributes class and added to Converter

With the NCGlobalAttributes class we manage all global attributes like an iterator to create the NetCDF file with the Converter. We assign these attributes trough the 'set' method in the Converter Class
Added String into App-**.js files

Added necesary String in various languages
ConverterServlet.java & converter.Form added

Added ConverterServlet and converter.Form simple structure