Skip decryption without key

Author: Kazuma TAKAOKA

.travis.yml

@@ -2,10 +2,10 @@ language: java
 jdk: oraclejdk8
 sudo: false
 before_install:
-  - openssl aes-256-cbc -K $encrypted_7726a8800684_key -iv $encrypted_7726a8800684_iv -in .travis/settings.xml.enc -out .travis/settings.xml -d
-  - openssl aes-256-cbc -K $encrypted_7726a8800684_key -iv $encrypted_7726a8800684_iv -in .travis/codesigning.asc.enc -out .travis/codesigning.asc -d
+  - if [ -n "$encrypted_7726a8800684_key" ]; then openssl aes-256-cbc -K $encrypted_7726a8800684_key -iv $encrypted_7726a8800684_iv -in .travis/settings.xml.enc -out .travis/settings.xml -d; fi
+  - if [ -n "$encrypted_7726a8800684_key" ]; then openssl aes-256-cbc -K $encrypted_7726a8800684_key -iv $encrypted_7726a8800684_iv -in .travis/codesigning.asc.enc -out .travis/codesigning.asc -d; fi
 dd:
-  - gpg --fast-import .travis/signingkey.asc
+  - if [ -f .travis/signingkey.asc ]; then gpg --fast-import .travis/signingkey.asc; fi
 install: true
 script:
   - mvn clean test -B