Implement keystore and add tests for it

[inetic]

implement: maid 1022
test: maid 1023

[maidsafe-highfive]

r? @benjaminbollen

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[coveralls]

Coverage increased (+0.42%) to 99.38% when pulling 5800943 on inetic:MAID-1022-implement-keystore into 06ae55b on maidsafe:master.

[coveralls]

Coverage increased (+0.42%) to 99.38% when pulling 5800943 on inetic:MAID-1022-implement-keystore into 06ae55b on maidsafe:master.

[coveralls]

Coverage increased (+0.42%) to 99.38% when pulling 05e347f on inetic:MAID-1022-implement-keystore into 06ae55b on maidsafe:master.

[coveralls]

Coverage increased (+0.42%) to 99.38% when pulling 05e347f on inetic:MAID-1022-implement-keystore into 06ae55b on maidsafe:master.

[benjaminbollen]

Nice work. I appreciate the fact that you check the self_signing. Also that you keep a set of the senders. That will be useful later on, when we want to derank nodes that provided false information.

[dirvine]

For sure, also when a node asks to Get something that is not there (especially StructuredData) it would be nice to filter the node for 10/20 minutes.

[dirvine]

What I mean is that if vaults or any upper layer returned a RoutingError::BanNode It then allows routing to make decisions on behaviour but also upper layers as well. Therefor we have routing rank etc. and vault rank (in our case) which is very neat.