GUACAMOLE-514: Correct username field type and add translations.

guacamole/src/main/webapp/translations/en.json

@@ -658,6 +658,7 @@
         "FIELD_HEADER_ENABLE_AUDIO"     : "Enable audio:",
         "FIELD_HEADER_ENABLE_SFTP"      : "Enable SFTP:",
         "FIELD_HEADER_HOSTNAME"         : "Hostname:",
+        "FIELD_HEADER_USERNAME"         : "Username:",
         "FIELD_HEADER_PASSWORD"         : "Password:",
         "FIELD_HEADER_PORT"             : "Port:",
         "FIELD_HEADER_READ_ONLY"        : "Read-only:",
@@ -677,7 +678,6 @@
         "FIELD_HEADER_SFTP_ROOT_DIRECTORY"        : "File browser root directory:",
         "FIELD_HEADER_SFTP_USERNAME"              : "Username:",
         "FIELD_HEADER_SWAP_RED_BLUE"    : "Swap red/blue components:",
-        "FIELD_HEADER_USERNAME"     : "Username:",
 
         "FIELD_OPTION_COLOR_DEPTH_8"     : "256 color",
         "FIELD_OPTION_COLOR_DEPTH_16"    : "Low color (16-bit)",