Git: Correctly handle aborting pull commands

For example, aborting a "git pull --rebase" command
did not work, because the old code tried to run
"git pull --abort" instead of "git rebase --abort".

As side effect, this patch also enables the Skip commit
button in handleMergeConflicts(), that was not shown
before.

Change-Id: Ifa43a4ba0199c97fdf8a361eb9e0207704d93e26
Reviewed-by: Orgad Shaneh <orgads@gmail.com>

src/plugins/git/gitclient.h

@@ -126,7 +126,8 @@ public:
 
     VcsBase::VcsCommand *vcsExecAbortable(const QString &workingDirectory,
                                           const QStringList &arguments,
-                                          bool isRebase = false);
+                                          bool isRebase = false,
+                                          QString abortCommand = QString());
 
     QString findRepositoryForDirectory(const QString &directory) const;
     QString findGitDirForRepository(const QString &repositoryDir) const;