Add Events API endpoint

[merenbach]

Closes #135 and addresses concerns about protobuf response object nomenclature.

Test as follows, replacing the resource name and resource uid as required:

curl '127.0.0.1:8080/api/v1/applications/guestbook/events?resName=guestbook-ui-5f455cc986-brbrz&resUid=9e0b4491-642a-11e8-81cf-08002774c671'

[jessesuen]

Can we name the field items and rename this to EventsList? I checked and we are starting to become inconsistent with our response objects in the case of lists. We currently already have ApplicationList, ClusterList, and RepositoryList. I think we should continue that convention:

// EventsList holds a list of resource events.
message EventsList {
	repeated k8s.io.api.events.v1beta1.Event items = 1;
}

Similarly the repository.ListDirResponse should probably change as well. For consistency sake I think we should change from:

// ListDirResponse returns the contents of the repo of a ListDir request
message ListDirResponse {
    repeated string data = 1;
}

to:

// FileList returns the file names of the repo of a ListDir request
message FileList {
    repeated string items = 1;
}

[alexmt]

I think this will return all events instead of events related to the specified resource. please fix it

[merenbach]

@alexmt right you are! I believe this is now addressed.

[alexmt]

I've realized that resource name is not enough to uniquely identify an object. Please add resource kind and use it in ListResourceEvents method.

[alexmt]

LGTM