Finished libpit 1.1.0. Added change operations (priority, category, etc)

Began unit testing of libpit.
Made most of the changes to pit-cli needed to incorporate the new libpit
features.

issues/pit-cli/0003c5.rst

@@ -0,0 +1,2 @@
+Add the ability to change an Issue's priority.
+==============================================

issues/pit-cli/0004c5.rst

@@ -0,0 +1,2 @@
+Add the ability to change an Issue's category.
+==============================================

issues/pit-cli/0005f4.rst

@@ -0,0 +1,2 @@
+Add the ability to create a new issue.
+======================================