Updated install notes for face-recognition

Signed-off-by: James Ketrenos <james_git@ketrenos.com>

README.md

@@ -1,4 +1,4 @@
-#### Upgrade to Node >v6
+#### Upgrade Node
 
 ```bash
 wget -qO- https://deb.nodesource.com/setup_8.x | sudo bash -
@@ -12,10 +12,18 @@ sudo npm install --global npm@latest
 sudo npm install --global polymer-cli
 sudo npm install --global bower
 ```
+
+# Install BLAS to improve performance, and dev tools so
+# face-recognition can build.
+
+```bash
+sudo apt install -y libopenblas-dev cmake
+```
+
 ###
 NEF processing uses ufraw-batch
 ```
-sudo apt install ufraw-batch
+sudo apt install -y ufraw-batch
 ```
 
 ### Create `photos` user for DB

face.js

@@ -13,6 +13,10 @@ const detector = fr.FaceDetector()
 
 console.log("Detecting faces...");
 const faceRectangles = detector.locateFaces(image)
+if (faceRectangles.length == 0) {
+	console.log("No faces found.");
+	process.exit(-1);
+}
 
 /* 200x200 picture faces */
 const faceImages = detector.detectFaces(image, 200)