[#33] Update testing EDSL examples

Description

Problem: we have some examples for testing EDSL and they use an old version of morley. We'd like to keep them up-to-date.

Solution: update morley version there, make them compile. Update testing EDSL doc accordingly. It turned out to be quite easy, there are only two breaking changes that required updates:

1. timestampFromSeconds now requires Integer.
2. Pushing a contract is now prohibited, so we use IMPLICIT_ACCOUNT.

Related issue(s)

Finishes #33 (closed)

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• Tests (see short guidelines)

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    • Haddock
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