Make possible to build library without curl and rsa signature -related files

add --with-curl flag
add preprocessor macroses, that
	allow to build without Service constructor, that uses default sendRequest
	allow to build completely without RSA_SHA1 signature
Update README.md, to describe --with-curl flag usage
Fix exception message in Signature class

fix exception message for unsupported signing method in Signature class
Fix README.md

README.md restructured
Use #ifdef in Service interface instead of throwing exception
Merge pull request #42 from swat32exe/make-curl-optional

Make curl and rsa signature optional
Add default constructor for Token

add Token default constructor, that leaves token and secret empty
Merge pull request #47 from swat32exe/add-default-token-ctor

Add default constructor for Token class
Remove line breaks from OAuth authorization header

function Utility::extractAuthorizationHeader now doesn't add line breaks
Merge pull request #54 from swat32exe/remove-line-breaks-in-oauth-header

Remove line breaks from OAuth authorization header
Implement single-level JSON parsing

add function parseSingleLevelJson, that parses JSON object, that doesn't contain nested objects or arrays, to map
Add tests, that check single level JSON parsing function
Fix coding style and typo

add spaces before keywords
rename singleLevelJSON_t to string_pair_t
fix typo in isValidUnquotedCharacter function name
replace == "" by .empty()
Move OAuth 1.0 sources to include/oauth and src/oauth folders
Fix indentation in ServiceConfiguration.h
Rename oauth folder to oauth1. Replace namespace OAuth with OAuth1

Move some files to the root of source and include folders.
Move OAuth 1.0 tests to test/oauth1 folder
Include missing header SingleLevelJSONTests.h
Fix JSON parsing

fix unicode character decoding
add comment about fitting unicode into char
Modify JSON parsing to throw exception for \uXXXX encoded characters

modify implementation
remove \uXXXX encoded character from test