Code Coverage Integration

[hiranya911]

Adding a new Maven profile for generating code coverage reports. The profile can be activated by running:

mvn test -Djacoco

This produces a set of HTML and CSV reports in the target/jacoco-ut directory. The CodeCoverageReporter class then parses the CSV report, and prints a summary to the console:

-------------------------------------------------------------------------
 Jacoco Coverage Report
-------------------------------------------------------------------------
com.google.firebase                                 1019/1271    80.17%
com.google.firebase.auth                            1231/1741    70.71%
com.google.firebase.auth.internal                     695/726    95.73%
com.google.firebase.cloud                               57/96    59.38%
com.google.firebase.database                        1176/3181    36.97%
com.google.firebase.database.collection             2179/2455    88.76%
com.google.firebase.database.connection              350/4776     7.33%
com.google.firebase.database.connection.util          175/614    28.50%
com.google.firebase.database.core                  5407/11422    47.34%
com.google.firebase.database.core.operation           353/517    68.28%
com.google.firebase.database.core.persistence       1596/2032    78.54%
com.google.firebase.database.core.utilities          751/1152    65.19%
com.google.firebase.database.core.view              2948/3485    84.59%
com.google.firebase.database.core.view.filter         852/929    91.71%
com.google.firebase.database.logging                  212/490    43.27%
com.google.firebase.database.snapshot               3159/3919    80.61%
com.google.firebase.database.tubesock                 13/2250     0.58%
com.google.firebase.database.util                     229/325    70.46%
com.google.firebase.database.utilities               602/1505    40.00%
com.google.firebase.database.utilities.encoding     1695/1947    87.06%
com.google.firebase.database.utilities.tuple             0/63     0.00%
com.google.firebase.internal                         468/1417    33.03%
com.google.firebase.tasks                           1205/1398    86.19%

Overall                                           26372/47711    55.27%

Judging by the numbers, we have our work cut out for us :)