Added database logging to RuntimeLogger.

[rmar3a]

• Runtime information related to contingency table generation is now written to a "CallLogs" table within the "_BN" database.
• Added methods to RuntimeLogger for writing logging information to the "CallLogs" table.
• Created a new script, logging.sql, that creates the "CallLogs" table, which is used to help log the runtimes for each method call that is related to contingency table generation.
• Renamed the method BuildCT_Pvars() to buildPVarsCounts() to match the naming format of the method buildRChainCounts().
• Updated the dbdump.sh script so that it ignores the CallLogs table when generating the mysql-extraction.txt file since the runtime values are expected to differ slightly between FactorBase runs.

[rmar3a]

As far as I can tell the reason why this pull request doesn't have the build status linked to it is because the Travis service is having issues: https://www.traviscistatus.com/incidents/rx6fhs3wqcln

Here is the associated build for this pull request, which passes: https://travis-ci.org/github/sfu-cl-lab/FactorBase/builds/667850892