Add Count method to BeeMap struct

This adds a Count() method to BeeMap struct that returns the number of
items within the safe map.

Modify func camelString() to be more robust

1. In previous edition, for case "pic_url_1", the func will return
"PicUrl_1", but "PicUrl1" seems to be more reasonable.
2. More test cases please refer to utils_test.go

Changing content type for template

Ability to register pre/post signal handlers

Remove a regression on AppPath

The application path is incorrect on Windows with the command line "go run". AppPath is assigned to the temp directory instead the folder project

set perm of rotated log to 440

statistics lock

Fix :supervisor work dir

policies implementation

Another Fix to #2263

resolves #2291, introduces AndNotCond/OrNotCond to orm.Condition

typo fix in comments, Getfiles-->GetFiles

Fix xml.GetSection() function which causes a panic

Fix http body may not be closed

beego/session: return proper error when session is not found

Parent errs was returned instead of err which is returned from the last
statement.

Update db_mysql.go instead of db.go, in order to avoid affect other database.

swagger: add 'Default' for Parameter

Rework getFlatParams for time.Time

Add RouterPattern to context.Input

Right now beego adds this param only in dev mode, but I noticed that it's very useful to have in prod environment to.
My current use case - filter that sends logs in newrelic. Pattern there will help a lot to generate correct transaction name.