Remove curl dependency

[bensmoif]

webdav-sync relies very tightly on command-line curl. We'd like to remove that dependency and have a built in async push and pull that does not require calls to curl.

[maboiteaspam]

As i m interested in this topic, i would like to suggest https://github.com/request/request / or https://github.com/substack/hyperquest modules to implement all http exchange logic.

IMHUnderstanding, in lib/webdav_sync.js we should keep only the public api and replace bodies with suggested modules.
The most problematic being the return value which today is the result of process.exec and won t remains the same.
Seems, to be confirmed, they are unused returns values, making the job easier.

BTW, how about using https://github.com/chalk/chalk to print pretty colors on std*** ?