Merge branch 'issue-20'
Fixed issue #23.

WARNING: Change in API for functions GetDiffClosedDays and GetDiffClosersDays
in ITS.R:
  - First parameter (period) removed, since it is no longer used.
  - Second (now first) parameter (init_date) is now "date".
Merge pull request #24 from VizGrimoire/issue-23

Fixed issue #23.
Rename data for unit tests
SCR: Added NEW, MERGED, ABANDONED and PENDING metrics using changes table from bicho
Merge branch 'master' of https://github.com/VizGrimoire/VizGrimoireR
SCR: Complete periods in pending data frame
SCM testing: update new results removing merge commits
General Stats tests: Update results after removing merge commits.  Improved fomatting.
SCR tests: Added tests for new, merged, abandoned functions workign with changes table.

The gerrit database should be updated in order to have changes data.
Be default not execute pending metric because it fails in old gerrit dbs
Add unit tests and data for CountBacklogTickets ITS function

Add unit tests and data about the issues_log table to calculate the
backlog of 'Open' + 'Reoponed' issues monthly and weekly.
Add R script to run the unit tests
Code refactoring for functions that complete with zeros

Two functions have been added to get the weeks and months between two
intervals of time. Those functions have been extracted from
completeZeroPeriod* and now are using also by other functions.
GetEvolBacklogTickets functions refactored

The function to the get evolution of the backlog by month or week
has been improved. Now it uses generic functions to the get the
periods (months or weeks) and accepts a list of statuses in order
to get the backlog for them.
Merge pull request #27 from VizGrimoire/backlog_of_issues_26

Code refactoring and tests for calculating the backlog of issues
Remove unit test from init_tests.R
Merge branch 'master' of github.com:VizGrimoire/VizGrimoireR
Functions moved to generic R file

GetPercentageDiff and GetDate functions moved to Auxiliary.R
Add unit tests for StaticNumSentIRC function