2.0.14: Update/Fix form-data/x-www-form-urlencoded snippets (#4)

* node-axios update application/form-data and x-www-form-urlencoded

* node axios minor touches,
node fetch placeholder path to file

* javascript axios multipart/form-data remove content-type header and handle file param as a file instead of base64

* case-insensitive removeProperty helper(currently used to remove "content-type" header)

* typo

* node-fetch - remove 'content-type' header and add spread formData headers on multipart/form-data

* update js-axios content-type header comment

* reusable params helper - construct params code,
checkIfRequestContainsFile general helper,
use URLSearchParams for x-www-form-urlencoded,
consistent code for node/js axios and fetch

* "encodedParams" also in js axios

* codeBuilder clone,
constructAppendedParamsCode same "append" method + options argument

* new helpers unit tests,
mocharc file(to take only spec files)

* insensitive case property remove test

* use lodash isObject,
check constructAppendedParamsCode test code result string

* constructAppendedParamsCode options argument tests