Add 'from_reader' for LoadAverage struct

[ludo-c]

Hello,

Thank you very much for this library ! It helps a lot !

Is it possible to add the possibility to read the load average from another directory than /proc please ?

This PR is inspired from the Meminfo struct, adding a method from_reader in the LoadAverage struct.

Tests are ok

test result: ok. 105 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 4.02s
test result: ok. 13 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 1.84s

Thank you !

[eminence]

Looks great, thank you!

[eminence]

This change has been published as version v0.14.0

[ludo-c]

Thank you very much !