Add LICENSE.txt file (#105)

* Correct typo in README.md

* Create License.txt file and fill in necessary data

* Update copyribght from 2016 to 2018

* Change license filename

LICENSE.txt

@@ -0,0 +1,7 @@
+Copyright (c) 2018 Quandl
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

README.md

@@ -1,4 +1,4 @@
-# Quandl Python Client 
+# Quandl Python Client
 [![Build Status](https://travis-ci.org/quandl/quandl-python.svg?branch=master)](https://travis-ci.org/quandl/quandl-python)
 [![PyPI version](https://badge.fury.io/py/quandl.svg)](https://badge.fury.io/py/quandl)
 
@@ -39,7 +39,7 @@ quandl.ApiConfig.api_version = '2015-04-09'
 
 ## Retrieving Data
 
-There are two methods for retrieving data in Python: the Quick method and the Detailed method. The latter is more suitable to application programming. Both methods work with Quandl's two types of data structures: time-series (dataset) data and non-time series (datatable). 
+There are two methods for retrieving data in Python: the Quick method and the Detailed method. The latter is more suitable to application programming. Both methods work with Quandl's two types of data structures: time-series (dataset) data and non-time series (datatable).
 
 The following quick call can be used to retrieve a dataset:
 
@@ -85,14 +85,14 @@ The following are instructions for running our tests:
 1. Make sure a version of python 2.7 or python 3.x is installed locally in your system. To avoid permission issues on OSX we recommend installing the packages from: https://www.python.org/downloads/
 2. Install `virtualenv` and `tox` using:
     `pip install tox virtualenv`
-3. Run following command (you may notice slow performance the first time): 
+3. Run following command (you may notice slow performance the first time):
     `python setup.py install`
 4. Run the following command to test the plugin in all versions of python we support:
     `tox`
 
 ## Recommended Usage
 
-We would suggest downloading the data in raw format in the highest frequency possible and preforming any data manipulation
+We would suggest downloading the data in raw format in the highest frequency possible and performing any data manipulation
 in pandas itself.
 
 See [this link](http://pandas.pydata.org/pandas-docs/dev/timeseries.html) for more information about timeseries in pandas.