Rust 1.33 warnings

[cholcombe973]

Just making a note of this so i don't forget.

   --> src/error.rs:116:48
    |
116 |             StorageError::CsvError(ref e) => e.cause(),
    |                                                ^^^^^

warning: use of deprecated item 'core::str::<impl str>::trim_left': superseded by `trim_start`
  --> src/telegraf.rs:98:68
   |
98 |                 let counter_value = line[end_index.unwrap() + 1..].trim_left();
   |                                                                    ^^^^^^^^^

warning: use of deprecated item 'core::str::<impl str>::trim_left': superseded by `trim_start`
  --> src/telegraf.rs:98:68
   |
98 |                 let counter_value = line[end_index.unwrap() + 1..].trim_left();
   |                                                                    ^^^^^^^^^