Changed exit codes to be > 0

ref: https://tldp.org/LDP/abs/html/exitcodes.html

- exit codes being -1 is a mistake that got perpetuated, should be 1 or greater
- for now, just use 1

core/server/ghost-server.js

@@ -166,7 +166,7 @@ class GhostServer {
             process.exit(0);
         } catch (error) {
             logging.error(error);
-            process.exit(-1);
+            process.exit(1);
         }
     }
 

core/server/index.js

@@ -164,7 +164,7 @@ const minimalRequiredSetupToStartGhost = async (dbState) => {
             } finally {
                 logging.error(err);
                 setTimeout(() => {
-                    process.exit(-1);
+                    process.exit(1);
                 }, 100);
             }
         }

index.js

@@ -37,6 +37,6 @@ ghost().then(function (ghostServer) {
 }).catch(function (err) {
     logging.error(err);
     setTimeout(() => {
-        process.exit(-1);
+        process.exit(1);
     }, 100);
 });