完成注册的界面。
Update NSString+Extenions.m

Add MD5 Function: + (NSString*)md5HexDigest:(NSString*)input
Update NSString+Extenions.h

ADD MD5 + (NSString*)md5HexDigest:(NSString*)inputStr;
Update JiaMian-Prefix.pch

Add header file for MD5: #import <CommonCrypto/CommonDigest.h>.
实现登录注册。
Merge branch 'register'

Conflicts:
	JiaMian.xcodeproj/project.pbxproj
	JiaMian/CommonMarco.h
	JiaMian/HomePageViewController.m
	JiaMian/MessageDetailViewController.m
	JiaMian/NSString+Extenions.h
	JiaMian/NSString+Extenions.m