Remove logrus and glog from most modules, keeping it only in bulk loaders. Instead switch to stubby like rpc tracing using net/tracer.

encoding. This helps us use the amazing context feature of grpc for RPC
tracing and client to server enforced deadlines.

Also upgrade the protobuf package so we can compile proto3.

Convert bytes to string before JSON encoding during ToJson. Switch to 2 servers. Add profiling info for loader.

Have a flag to forbit mutations on a server. Very useful for the live demo, or other read-only situations.

Changing type of value from interface to []byte

Making sure tests pass.

Addressing todo and fixing tests in query_test.go

Removing parseValue function.

Enable vendoring using GOVENDOR

Benchmarking

Resolves - https://discuss.dgraph.io/t/vendoring-dependencies-for-dgraph/177

Pertaining to the discussion mentioned above: GLOCKFILE has been removed,
README has been updated, and vendor/vendor.json has been added. At this
point of time we are only adding dependency information file(vendor.json) and
not the actual dependencies. This commit also helps avoiding
installation of dependencies in $GOPATH if vendor directory is synced
using govendor.

1. Changing extension of files with binary data to .bin.
2. Running separate benchmark for each query according to numElements in their
result.