Update gRPC server, it's output is now similar to CLI output

• Add [#22]: Go module support for more stable builds
• Add [#19]: bring gRPC output close to cli output. Breaks backward
  compatibility of gRPC.
• Add [#20]: update API interaction with gnindex.
• Add [#17]: return offsets for the start and the end of name-strings.
• Fix [#18]: gRPC works with diacritics in text input.

gRPC server and Docker support

• Add: [#16]: docker support. Command make docker creates docker image.
• Add: [#15]: enable gRPC to set data-source IDs for verification
• Add: [#14]: setting for name verification data-sources as well as command
  line flag. Currently tests for gRPC are located in [Ruby gem gndinder]
  project.
• Add: [#12]: gRPC-based HTTP API to access gnfinder from other languages.
• Add: StemEditDistance for fuzzy matching by stem.

Improvements in verification

• Add [#11]: Quality Summary and Preferred data sources in verification

• Add [#9]: Additional information how to install in README.md

• Add [#8]: Retry verification if any error happens in the process.

• Add [#7]: Add EditDistance field to verification output.

• Add [#6]: Add 'NoMatch' value to verification 'MatchType'.

• Fix [#5]: Hide verification "data" if it is empty.

• Remove [#6]: Remove Verified field, as it repeats 'NoMatch' information.

v0.5.1

Fix #4: Retry verification if timeout