Common-utils-py

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* Fix bug in metadata index

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* Fix index number in service agreements

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* Fix compute template

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* Add compute template

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* Add setter for service endpoint.

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* Update methods to changes in the different OEP's
- [OEP7](https://github.com/oceanprotocol/OEPs/tree/master/7/v0.2)
- [OEP8](https://github.com/oceanprotocol/OEPs/tree/master/8/v0.4)
- [OEP11](https://github.com/oceanprotocol/OEPs/tree/master/11/v0.2)
- [OEP12](https://github.com/oceanprotocol/OEPs/tree/master/12)
- [OEP13](https://github.com/oceanprotocol/OEPs/tree/master/13)