Add init tablespace size and avoid duplication of plans

Changes:
* made the 'name' column unique in the Plan to avoid recreation/duplication of plans at restart of the service broker A
* added an initial size for the tablespace (rather than the default 10MB) just so its bigger/configurable by user. 
* when registering with marketplace, suspect the space inside "Oracle XE" appeared to cause some problem. So, changed it in the service definition template. Ignore this last part if you dont see any issues.