Duplicated actions in the run of e2e tests on CircleCI

[akolotov]

As part of the initial integration to the monorepo both sets of e2e tests for the oracle (#45) and for the UI (#54) were added to CircleCI.

From the CI process point of view both e2e test environment performs the following set of actions:

• pull parity docker image
• pull redis db docker image
• pull rabbitmq docker image
• pull node.js docker image
• prepare Linux on the oracle image to resolve dependencies
• resolve dependencies to run the oracle
• install dependencies to compile contracts
• compile contracts
• install dependencies to deploy contracts
• deploy contracts

It definitely increases time of the e2e tests and cause redundant load on the testing system.

Consider to optimize the process of running e2e testing on CircleCI in order to reduce number of duplicated actions.