Prepare for v1.4.0 release

Update release notes and various version stamps.

Signed-off-by: David Brown <david.brown@linaro.org>

README.md

@@ -6,7 +6,7 @@
 [coverity]: https://scan.coverity.com/projects/mcuboot
 [travis]: https://travis-ci.org/JuulLabs-OSS/mcuboot
 
-This is mcuboot, version 1.4.0-rc2
+This is mcuboot, version 1.4.0
 
 MCUboot is a secure bootloader for 32-bit MCUs.   The goal of MCUboot is to
 define a common infrastructure for the bootloader, system flash layout on

repository.yml

@@ -26,7 +26,7 @@ repo.versions:
     "1.2.0": "v1.2.0"
     "1.3.0": "v1.3.0"
     "1.3.1": "v1.3.1"
-    "1.4.0": "v1.4.0-rc2"
+    "1.4.0": "v1.4.0"
 
     "0-dev": "0.0.0"        # master
     "0-latest": "1.3.1"     # latest stable release

scripts/imgtool/__init__.py

@@ -12,4 +12,4 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-imgtool_version = "1.4.0rc2"
+imgtool_version = "1.4.0"

version.yml

@@ -19,4 +19,4 @@
 
 # Newt uses this file to determine the version of a checked out repo.
 # This should always be 0.0.0 in the master branch.
-repo.version: 0.0.0
+repo.version: 1.4.0