set cookie string on the reponse object.
1. supporting Excel 2007 format(.xlsx) to download a excel file that has rows
more than 64k
2. reducing memory pressure by using SXSSF. SXSSF does not use DOM model
and write out rows when the number of rows are above a fixed window
size.
Merge remote-tracking branch 'codelibs/master' into hotfixes/sxssf_xlsx

Conflicts:
	pom.xml
	src/main/java/org/codelibs/elasticsearch/df/content/xls/XlsContent.java
Merge pull request #5 from CHOIJAEHONG1/hotfixes/sxssf_xlsx

Improvement for Excel.