Modify SpecInfra::Backend::Exec#build_command

Now we transform the given shell command into `/bin/sh -c #{cmd}`,
so that we don't need to parse shell syntax.
Update spec for SpecInfra::Backend::Exec#build_command
Add Fedora as a separate OS
Support SysV for Fedora 14 and under and share common functions with RedHat
Add constraint ruby version because rake 10.2 does not support Ruby 1.8
anymore
Remove allow_failures
Added the constraint to the wrong line
Return SpecInfra::CommandResult object when method name not start with
`check_`
Merge pull request #71 from serverspec/return-result-object

Return SpecInfra::CommandResult object when method name not start with `check_`
Add get_ipaddress_of_host command
Merge pull request #72 from serverspec/add-get_ipaddress_of_host

Add get_ipaddress_of_host command
Bump up version
Add get_file_content to windows command
Fix broken indent
Add architecture option that switches x86/x64 powershell
Merge pull request #73 from murank/add_get_file_content

Add get_file_content to windows command
Merge pull request #74 from murank/fix_broken_indent

Fix broken indent
Merge pull request #75 from murank/add_architecture_option

Add architecture option that switches x86/x64 powershell
Bump up version
Add constrain to octokit version because latest octokit requires Ruby >= 1.9.2