JIRA can't produce TimeSheet Report if the Hours per day value has decimal

JIRA will throw System Error if 'Hours per day' is set with a value than contain decimal when user want to generate the Time Sheet Report.

Here are the steps to reproduce the problem:

1. set the Hours per day via Administration > Global Settings > Time Tracking to 7.5.
2. create a project
3. go to the Projects > select the newly created project > click on Reports > select Time Sheet Report
4. select any Start Date,End Date,User and click on the "Next" button.
5. JIRA will throw System Error which contain the following Stack Trace:

   java.lang.NumberFormatException: For input string: "7.5"
   	at java.lang.NumberFormatException.forInputString(NumberFormatException.java:48)
   	at java.lang.Integer.parseInt(Integer.java:458)
   	at java.lang.Integer.<init>(Integer.java:660)
   	at com.fdu.jira.util.TextUtil.<init>(TextUtil.java:43)
   	at com.fdu.jira.plugin.report.timesheet.TimeSheet.generateReport(TimeSheet.java:454)
   	at com.fdu.jira.plugin.report.timesheet.TimeSheet.generateReportHtml(TimeSheet.java:472)
   ...