Refactored the man.1 and added missing section

Uses convention from man-pages(7)[1].

[1]: http://man7.org/linux/man-pages/man7/man-pages.7.html
English fixes
Added a test for map a path that has been already mapped
Fixed map a path that has been already mapped
Fixed AppVeyor configuration to speed up the build process

* AppVeyor build only on 64 Bits OS

* Use the installed appveyor git
minor #64 Fixed AppVeyor configuration to speed up the build process (alquerci)

This PR was merged into the 1.1-dev branch.

Discussion
----------

| Q               | A
| --------------- | ---
| Bug fix?        | no
| New feature?    | no
| BC breaks?      | no
| Deprecations?   | no
| Tests pass?     | yes
| Related tickets | #38
| License         | GNU GPLv3

Commits
-------

8a3efe9 Fixed AppVeyor configuration to speed up the build process
minor #43 Refactored the man.1 and added missing section (alquerci)

This PR was merged into the 1.1-dev branch.

Discussion
----------

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Related tickets |
| License       | GNU GPLv3

Uses convention from [man-pages(7)][1].

- [x] Fixed spelling by a native English speaker, @nylen.

[1]: http://man7.org/linux/man-pages/man7/man-pages.7.html

Commits
-------

fcceaa7 English fixes
226e6a9 Refactored the man.1 and added missing section
bug #63 Fixed map a path that has been already mapped (alquerci)

This PR was merged into the 1.1-dev branch.

Discussion
----------

| Q               | A
| --------------- | ---
| Bug fix?        | yes
| New feature?    | no
| BC breaks?      | no
| Deprecations?   | no
| Tests pass?     | yes
| Related tickets |
| License         | GNU GPLv3

It appears after `setup` that read the `/etc/setup/setup.rc` file with Windows path for the cache directory ([ref][0]).

[0]: https://ci.appveyor.com/project/alquerci/cyg-apt/build/1.0.190/job/4c85isv4adi9e3kl#L842

Commits
-------

72f75cf Fixed map a path that has been already mapped
fea26d7 Added a test for map a path that has been already mapped
Removed custum usage message on parse error

When the user sends wrong command line arguments the default behavior from
`argparse` python standard module is executed.
Removed the duplicated code for parsing the configuration file

At several places in the code logic is implemented to read the configuration.

The solution is to remove this duplication by pooling the business logic into
a single function (eg `parse_rc`).

Finally it will be better to read the configuration only once.
Improved the steps clarity into the main

Steps on the main are a little unclear.

So adding some comments to explain what's happening.

In the future it should be better to avoid writing a lot of code in it.