Standardize task file names

Update task files names to match standard naming convention of OSA
roles.

Change-Id: I975f855cccf4583946e9851728637ae96d8c9598

tasks/main.yml

@@ -22,20 +22,20 @@
   tags:
     - always
 
-- include: pre-install.yml
+- include: rally_pre_install.yml
   tags:
     - rally-install
 
-- include: install.yml
+- include: rally_install.yml
   tags:
     - rally-install
 
-- include: post-install.yml
+- include: rally_post_install.yml
   tags:
     - rally-install
     - rally-config
 
-- include: database-setup.yml
+- include: rally_db_setup.yml
   when: inventory_hostname == groups[rally_role_project_group][0]
   tags:
     - rally-install

tasks/rally_install.yml

@@ -13,7 +13,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-- include: install-apt.yml
+- include: rally_install_apt.yml
   static: no
   when: ansible_pkg_mgr == 'apt'