Changes and improvements in credentials insertion page

TASMAN-core/src/main/java/it/inaf/ia2/tsm/TapSchema.java

.../src/main/java/it/inaf/ia2/tsm/datalayer/Credentials.java

...re/src/main/java/it/inaf/ia2/tsm/model/PropertyModel.java

.../src/main/java/it/inaf/ia2/tsm/model/TapSchemaModels.java

TASMAN-core/src/main/java/it/inaf/ia2/tsm/model/Tasman.java

...ain/java/it/inaf/ia2/tsm/webapp/ConfigurationManager.java

.../main/java/it/inaf/ia2/tsm/webapp/CredentialsEditing.java

...in/java/it/inaf/ia2/tsm/webapp/env/ApplicationConfig.java

...app/src/main/java/it/inaf/ia2/tsm/webapp/env/UIModal.java

...a/it/inaf/ia2/tsm/webapp/xmlconfig/JoinedCredentials.java

...t/inaf/ia2/tsm/webapp/xmlconfig/SeparatedCredentials.java

...java/it/inaf/ia2/tsm/webapp/xmlconfig/TapCredentials.java

TASMAN-webapp/src/main/webapp/credentialsEditing.xhtml

TASMAN-webapp/src/main/webapp/resources/js/credentials.js