Starting to add implementations of API.

Going agile: starting from partial parsing of the input file, capturing commit
hashes and inserting them in the Commit container.
Added Author and Date parsing.
Added parsing of Committer.
Added parsing of changed files.
Merge branch 'GitStatistics'
Making explicit use of istringstream.
Merge branch 'master' of github.com:luisibanez/CommunityAnalyzer
Added Date parsing with strptime and chrono.
Populated and tested people container.
Merge branch 'GitStatistics'