Drop table if needed

[AtulDwivedi]

If tables are already existing and need to be deleted while deploying the application in order to simulate client like application start-up process then drop the existing tables.

• Have a context param in web.xml
• Read it in ContextListener
• If tables need to be dropped as per the parameter, have a method in SchemaDaoImpl to drop the tables

Tables to be dropped must be application table
Dropping should happen before table creation

[AtulDwivedi]

• Added context param in web.xml
• Reading the same in ContextListener and calling SchemaDaoImpl.dropTables
• In SchemaDaoImpl.dropTables
  -- Fetching all DB tables
  -- Application tables from h2.sql file
  -- If application table exists in DB then dropping the same