Update VERSION file of agent to LATEST_VERSION

cr https://code.amazon.com/reviews/CR-26866900

Author: Anandaraju Coimbatore Sivaraju

bin/install

@@ -317,7 +317,7 @@ end
 
   def get_target_version(target_version, type, region, bucket)
     if target_version.nil?
-      version_file_key = 'latest/VERSION'
+      version_file_key = 'latest/LATEST_VERSION'
       version_data = get_version_file_from_s3(region, bucket, version_file_key)
       if version_data.include? type
         return version_data[type]

bin/update

@@ -439,7 +439,7 @@ EOF
 
   REGION = get_region
   BUCKET = "aws-codedeploy-#{REGION}"
-  VERSION_FILE_KEY = 'latest/VERSION'
+  VERSION_FILE_KEY = 'latest/LATEST_VERSION'
 
   NO_AGENT_INSTALLED_REPORTED_WINDOWS_VERSION = 'No Agent Installed'
   def running_agent_version_windows