Fixed snap versioning

I have found a bug in the snap versioning feature. After compiled php 5.3.27 and 5.5.3 and wanted to select 5.3 I got this:

```
$ php-version 5.3
SWITCHED PHP VERSION TO: 5.5.3
NEW PHP ROOT DIRECTORY : /opt/php/versions/5.5.3
```

When I entered the find separately I got this:
```
$ find $PHP_VERSIONS -type d -maxdepth 1 -mindepth 1 -exec basename {} \; | grep 5.3

find: warning: you have specified the -maxdepth option after a non-option argument -type, but options are not positional (-maxdepth affects tests specified before it as well as those specified after it).  Please specify options before other arguments.

find: warning: you have specified the -mindepth option after a non-option argument -type, but options are not positional (-mindepth affects tests specified before it as well as those specified after it).  Please specify options before other arguments.

5.5.3
5.3.27
```

The grep matched 5. __5.3__ and __5.3__ .27. With this patch the grep matches from the beginning of the string and also fixed the warning.