Package env for working with environment variables inside Beego

Add GetCond func to querySet

The package env makes it trivial to work with environment variables.
It allows getting values with defaults as a fallback.
New ENV variables can be set safely on the current process environment.

avoid creating tmp files to read/parse config

There is no need to create new file in ParseData(data []byte) (Configer, error).Tet's make code simply.

content-length not set in case EnableGZIP=true

This results in responses with Content-Type as gzip as opposed to original content type.
This affects ServeJSON() function.

Fixed typo in orm/models_boot.go

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