ogma-core: Reimplement DB parser using JSON Spec parser. Refs #122.

[ivanperez-keera]

Replace the ad hoc DB parser with a parser based on the generic JSON parser, as prescribed in the solution proposed for #122.

[ivanperez-keera]

Change Manager: The function decode is imported but not really used in the code. It is necessary to review the implementation to minimize the introduction of technical debt (even if, extensionally, it works).

[ivanperez-keera]

Implementor: Fix implemented, review requested.

[ivanperez-keera]

Change Manager: Verified that:

• Solution is implemented:
  • The code proposed compiles passes the tests. Details:
    Docker image:

    FROM ubuntu:trusty
    
    RUN apt-get update
    
    RUN apt-get install --yes software-properties-common
    RUN add-apt-repository ppa:hvr/ghc
    RUN apt-get update
    
    RUN apt-get install --yes ghc-8.6.5 cabal-install-2.4
    RUN apt-get install --yes libz-dev
    
    ENV PATH=/opt/ghc/8.6.5/bin:/opt/cabal/2.4/bin:$PWD/.cabal-sandbox/bin:$PATH
    
    RUN cabal update
    RUN cabal v1-sandbox init
    RUN cabal v1-install alex happy
    RUN apt-get install --yes git
    
    # We install the application first and then test it, in case any tests need to
    # run the tool.
    CMD git clone $REPO && \
        cd $NAME && \
        git checkout $COMMIT && \
        cd .. && \
        cabal v1-install $NAME/$PAT**/ --enable-tests && \
        cabal v1-install $NAME/$PAT**/ --enable-tests --run-tests -j1

    Command:

    $ docker run -e "REPO=https://github.com/NASA/ogma" -e "NAME=ogma" -e PAT="ogma-" -e "COMMIT=a590ae61f83e2a91fbbd4b5212caa228c3c0cf07" -it ogma-test

  • The solution proposed fixes the issues described. Details:
    Not applicable (not a bug). The tests above run the parser modified as part of this PR on a test file.
• Implementation is documented. Details:
  No changes needed.
• Change history is clear.
• Commit messages are clear.
• Changelogs are updated.
• Examples are updated. Details:
  No examples affected.
• Required version bumps are evaluated. Details:
  Bump needed (libraries disappear).