Update for latest Rust
Merge pull request #105 from Arcterus/master

Update for latest Rust
Move util.rs to common
Groom id/id.rs to work with util.rs
whoami and id use c_types
Merge pull request #107 from alan-andrade/common

/common for code reusability
Make the capitalization of Rust consistent
logname implementation
Merge pull request #110 from humboldtux/master

logname implementation
Update for new programs
id and groups share functions
Merge pull request #114 from alan-andrade/groups

Groups
Fix for latest Rust
Merge pull request #115 from Arcterus/master

Fix for latest Rust
Implement tac (closes #117)
Remove a couple of programs from the to-do list
Merge pull request #118 from Arcterus/tac

Implement tac (closes #117)
tac: fix an issue with --separator
Merge pull request #119 from Arcterus/tac

tac: fix an issue with --separator
Add paste (closes #120)