#66 partial implement xorm_cache tag

add Engine.disableGlobalCache and explicit using cache via xorm_cache tag
Merge remote-tracking branch 'origin/master' into feature/cacher-tag
Merge remote-tracking branch 'origin/master' into feature/cacher-tag
Merge remote-tracking branch 'origin/master' into feature/cacher-tag
add Engine.LogSQLQueryTime and Engine.LogSQLExecutionTime for SQL execution time logging
redis cacher implementation, incomplete
Merge remote-tracking branch 'origin/master' into feature/cacher-tag
implemented interface gob encode and decode for redit cacher
bug fixed #154
Merge branch 'master' of github.com:go-xorm/xorm
fix error using ioutil.Discard
resolved merge
code tidy up

logger tidy up

private serialize and deserialize func
bugfix

Signed-off-by: 商讯在线 <swhbox@foxmail.com>
update func (session *Session) cacheFind, if no cache hit, continue instead of return error
Merge branch 'master' of github.com:go-xorm/xorm
bug fixed for Desc & Asc
All cols not being reset, causes problems when using the session again after AllCols()

Signed-off-by: Alfred Hall <ahall@ahall.org>
Merge pull request #158 from ahall/master

All cols not being reset, causes problems when using the session again a...
guard uninitialized time in  func (engine *Engine) TZTime(t time.Time)