fixed i18n issues

src/checkstyle/com/puppycrawl/tools/checkstyle/checks/HeaderCheck.java

@@ -60,7 +60,7 @@ public class HeaderCheck
     public void beginTree()
     {
         if (mHeaderLines == null) {
-            log(1, "Unable to check as missing lines to check.");
+            log(1, "header.spec.missing");
             return;
         }
 

src/checkstyle/com/puppycrawl/tools/checkstyle/checks/SimplifyBooleanExpressionCheck.java

@@ -72,8 +72,7 @@ public class SimplifyBooleanExpressionCheck
             case TokenTypes.LOR:
             case TokenTypes.LAND:
                 log(parent.getLineNo(), parent.getColumnNo(),
-                        // TODO: i18n
-                        "Expression can be simplified.");
+                        "simplify.expression");
                 break;
             default:
                 break;

src/checkstyle/com/puppycrawl/tools/checkstyle/checks/SimplifyBooleanReturnCheck.java

@@ -67,10 +67,7 @@ public class SimplifyBooleanReturnCheck
         if (returnsOnlyBooleanLiteral(thenStatement)
             && returnsOnlyBooleanLiteral(elseStatement))
         {
-            // TODO: i18n
-            log(aAST.getLineNo(),
-                aAST.getColumnNo(),
-                "Remove conditional logic.");
+            log(aAST.getLineNo(), aAST.getColumnNo(), "simplify.boolreturn");
         }
     }
 

src/checkstyle/com/puppycrawl/tools/checkstyle/checks/messages.properties

@@ -46,6 +46,7 @@ instantiation.avoid=Avoid instantiation of {0}.
 
 upperEll=Should use uppercase ''L''.
 
+header.spec.missing=Unable to check as missing lines to check.
 header.missing=Missing a header - not enough lines in file.
 header.mismatch=Line does not match expected header line of ''{0}''.
 
@@ -66,4 +67,7 @@ equals.noHashCode=Definition of ''equals()'' without corresponding defnition of
 
 hidden.field=''{0}'' hides a field.
 
-translation.missingKey=Key ''{0}'' missing.
+translation.missingKey=Key ''{0}'' missing.
+
+simplify.expression=Expression can be simplified.
+simplify.boolreturn=Remove conditional logic.