Adding a script to check for line endings (valid UNIX ending)

-Created a bash script using grep to check for carriage return at line endings.
-Works for modified and new files only (if choosen)
-Modified build_and_run.sh to include the new check.sh and run it.

dist/tools/endingcheck/check.sh

+#!/bin/bash
+#
+# Copyright (C) 2015 Kushal Singh <kushal.spiderman.singh@gmail.com>
+#
+# This file is subject to the terms and conditions of the GNU Lesser
+# General Public License v2.1. See the file LICENSE in the top level
+# directory for more details.
+#
+
+BRANCH=${1}
+ENDREGEX='^M$'
+
+# If no branch but an option is given, unset BRANCH.
+# Otherwise, consume this parameter.
+if echo "${BRANCH}" | grep -q '^-'; then
+    BRANCH=""
+else
+    if [ -n "${BRANCH}" ]; then
+        shift 1
+    fi
+fi
+
+# If the --diff-filter option is given, consume this parameter.
+# Set the default DIFFFILTER option otherwise.
+DIFFFILTER="${1}"
+if echo "${DIFFFILTER}" | grep -q '^--diff-filter='; then
+    shift 1
+else
+    DIFFFILTER="--diff-filter=ACMR"
+fi
+
+# select either all or only touched-in-branch files, filter through FILEREGEX
+if [ -z "${BRANCH}" ]; then
+    FILES="$(git ls-tree -r --full-tree --name-only HEAD)"
+else
+    FILES="$(git diff ${DIFFFILTER} --name-only ${BRANCH})"
+fi
+
+if [ -z "${FILES}" ]; then
+    exit
+fi
+
+grep -E -R -l ${ENDREGEX} ${FILES} > /dev/null
+
+if [ $? -eq 0 ]
+then
+    echo "ERROR: carriage return error found"
+    exit 1
+else
+    exit 0
+fi

dist/tools/travis-scripts/build_and_test.sh

@@ -45,6 +45,9 @@ then
         ./dist/tools/externc/check.sh master
         RESULT=$(set_result $? $RESULT)
 
+        ./dist/tools/endingcheck/check.sh riot/master --diff-filter=MA
+        RESULT=$(set_result $? $RESULT)
+
         # TODO:
         #   Remove all but `master` parameters to cppcheck (and remove second
         #   invocation) once all warnings of cppcheck have been taken care of