Adding rule for checkstyle line lenght.

Confguration taken from :
https://github.com/checkstyle/checkstyle/blob/master/src/main/resources/google_checks.xml

Change-Id: If4aa4c33db36f7f892adeed28133f3bf68b41a44
diff --git a/eclipse/settings/code-style/gwt-checkstyle.xml b/eclipse/settings/code-style/gwt-checkstyle.xml
index 671974a..d146bb0 100644
--- a/eclipse/settings/code-style/gwt-checkstyle.xml
+++ b/eclipse/settings/code-style/gwt-checkstyle.xml
@@ -23,6 +23,10 @@
     </module>
     <module name="TreeWalker">
        <property name="fileExtensions" value="java"/>
+       <module name="LineLength">
+            <property name="max" value="100"/>
+            <property name="ignorePattern" value="^package.*|^import.*|a href|href|http://|https://|ftp://"/>
+       </module>
        <module name="FileContentsHolder" />
        <module name="InterfaceIsType">
             <property name="severity" value="ignore"/>