### What is this PR for?
This is to give Windows first-class support for running Zeppelin without the need for Cygwin or other hacks.
### What type of PR is it?
Improvement
### Todos
* [x] - Fix notebook dir path handling which right now assumes URI compatible string (see https://github.com/apache/incubator-zeppelin/blob/master/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/VFSNotebookRepo.java#L63)
* [x] - Add documentation for configuring and running on Windows
* [x] - Independent code review of the CMD scripts to ensure they're correct
### Is there a relevant Jira issue?
ZEPPELIN-647
### How should this be tested?
* Pull this PR
* Build
* Override default ZEPPELIN_NOTEBOOK_DIR in zeppelin-env.cmd to be an absolute file URI such as file:///c:/notebook
* Start with bin\zeppelin.cmd
* If using any Hadoop system ensure you have winutils.exe in your HADOOP_HOME\bin, see (https://github.com/steveloughran/winutils)
### Screenshots (if appropriate)
### Questions:
* Does the licenses files need update? No
* Is there breaking changes for older versions? No
* Does this needs documentation? Yes
Author: Silvio Fiorito <silvio.fiorito@granturing.com>
Author: Silvio Fiorito <Silvio Fiorito>
Closes#734 from granturing/windows-support and squashes the following commits:
8aadd45 [Silvio Fiorito] Fixes to handle spaces in paths properly, both for ZEPPELIN_HOME and CLASSPATH
73aaf4f [Silvio Fiorito] Default to the appropriate interpreter when running on Windows
db28fe9 [Silvio Fiorito] Support for running unit tests on Windows using the appropriate interpreter script
a1e3097 [Silvio Fiorito] Support for Windows CMD shell interpreter
82acdcf [Silvio Fiorito] Merge branch 'master' into windows-support
9e8b309 [Silvio Fiorito] Initital doc updates for running on Windows
03baf62 [Silvio Fiorito] Additional fix for embedded pyspark environment variables
2b9f01c [Silvio Fiorito] Fix for pyspark PYTHONPATH environment variable not being set properly due to delayed expansion
c700808 [Silvio Fiorito] Check for Windows path before creating URI to prevent URISyntaxExecption
d30e4b9 [Silvio Fiorito] And again fix indentations missed last time
5b49d3e [Silvio Fiorito] Cleaned up indentation
9e40482 [Silvio Fiorito] Initial support for Windows platform, startup scripts
