Issue title: 虚拟机下CentOS6.5下ltp_server无法开启
 Issue body: [root@CentOS01 bin]# ./ltp_server --port 3434
[INFO] 2016-06-20 19:22:50 Loading segmentor model from "ltp_data/cws.model" ...
[INFO] 2016-06-20 19:22:59 segmentor model is loaded.
[INFO] 2016-06-20 19:22:59 Loading postagger model from "ltp_data/pos.model" ...
[INFO] 2016-06-20 19:23:20 postagger model is loaded
[INFO] 2016-06-20 19:23:20 Loading NER resource from "ltp_data/ner.model"
[INFO] 2016-06-20 19:23:21 NER resource is loaded.
[INFO] 2016-06-20 19:23:21 Loading parser resource from "ltp_data/parser.model"
[INFO] 2016-06-20 19:23:39 parser is loaded.
[INFO] 2016-06-20 19:23:39 Loading SRL resource from "ltp_data/srl/"
[INFO] 2016-06-20 19:23:41 SRL resource is loaded.

 Comments: 
 Comment 0: 加载到 SRL resource 后面就不执行了

 Comment 1: 这样就表示server已经开启，waiting request中

{'source': 'GithubIssues', 'repo_name_with_owner': 'HIT-SCIR/ltp', 'issue_id': 161112252, 'repo_stars': 4129.0}