Add version api for halo application

src/main/java/run/halo/app/config/HaloConfiguration.java

@@ -97,7 +97,7 @@ public class HaloConfiguration {
                                                                OptionService optionService) {
         ContentFilter contentFilter = new ContentFilter(haloProperties, optionService);
         contentFilter.setFailureHandler(new ContentAuthenticationFailureHandler());
-        contentFilter.addExcludeUrlPatterns("/api/*", "/install", "/admin/*", "/js/*", "/css/*");
+        contentFilter.addExcludeUrlPatterns("/api/*", "/install", "/version", "/admin/*", "/js/*", "/css/*");
 
         FilterRegistrationBean<ContentFilter> contentFrb = new FilterRegistrationBean<>();
         contentFrb.addUrlPatterns("/*");

src/main/java/run/halo/app/controller/admin/api/AdminController.java

@@ -66,4 +66,5 @@ public class AdminController {
     public AuthToken refresh(@PathVariable("refreshToken") String refreshToken) {
         return adminService.refreshToken(refreshToken);
     }
+
 }

src/main/java/run/halo/app/controller/content/MainController.java

@@ -1,7 +1,9 @@
-package run.halo.app.controller.content.api;
+package run.halo.app.controller.content;
 
 import org.springframework.stereotype.Controller;
 import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.ResponseBody;
+import run.halo.app.model.support.HaloConst;
 
 /**
  * Admin page.
@@ -22,4 +24,10 @@ public class MainController {
     public String installation() {
         return "redirect:/admin/index.html#install";
     }
+
+    @GetMapping("/version")
+    @ResponseBody
+    public String version() {
+        return HaloConst.HALO_VERSION;
+    }
 }

src/main/java/run/halo/app/model/support/HaloConst.java

@@ -76,6 +76,7 @@ public class HaloConst {
     public static String USER_SESSION_KEY = "user_session";
 
     static {
+        // Set version
         HALO_VERSION = HaloConst.class.getPackage().getImplementationVersion();
     }
 }