gtest genesis parsing

• only embed chainspec when feature enabled
• change existential deposit to match g1v1
• adapt genesis parsing to real-world data

# build with gtest feature
cargo build --release --features gtest --no-default-features
# run with custom genesis
DUNITER_GTEST_GENESIS=~/dev/py-g1-migrator/output/gtest_genesis.json duniter --tmp --alice --chain=gtest_dev

node/src/chain_spec/gdev.rs

@@ -339,11 +339,11 @@ fn gen_genesis_for_local_chain(
     assert!(initial_smiths_len <= initial_identities_len);
     assert!(initial_authorities_len <= initial_smiths_len);
 
-    let babe_epoch_duration = get_env_u32("DUNITER_BABE_EPOCH_DURATION", 30) as u64;
-    let cert_validity_period = get_env_u32("DUNITER_CERT_VALIDITY_PERIOD", 1_000);
-    let membership_period = get_env_u32("DUNITER_MEMBERSHIP_PERIOD", 1_000);
-    let smith_cert_validity_period = get_env_u32("DUNITER_SMITH_CERT_VALIDITY_PERIOD", 1_000);
-    let smith_membership_period = get_env_u32("DUNITER_SMITH_MEMBERSHIP_PERIOD", 1_000);
+    let babe_epoch_duration = get_env("DUNITER_BABE_EPOCH_DURATION", 30) as u64;
+    let cert_validity_period = get_env("DUNITER_CERT_VALIDITY_PERIOD", 1_000);
+    let membership_period = get_env("DUNITER_MEMBERSHIP_PERIOD", 1_000);
+    let smith_cert_validity_period = get_env("DUNITER_SMITH_CERT_VALIDITY_PERIOD", 1_000);
+    let smith_membership_period = get_env("DUNITER_SMITH_MEMBERSHIP_PERIOD", 1_000);
     let ud_creation_period = get_env("DUNITER_UD_CREATION_PERIOD", 60_000);
     let ud_reeval_period = get_env("DUNITER_UD_REEEVAL_PERIOD", 1_200_000);
     let ud = 1_000;
@@ -505,11 +505,11 @@ fn gen_genesis_for_benchmark_chain(
     assert!(initial_smiths_len <= initial_identities_len);
     assert!(initial_authorities_len <= initial_smiths_len);
 
-    let babe_epoch_duration = get_env_u32("DUNITER_BABE_EPOCH_DURATION", 30) as u64;
-    let cert_validity_period = get_env_u32("DUNITER_CERT_VALIDITY_PERIOD", 1_000);
-    let membership_period = get_env_u32("DUNITER_MEMBERSHIP_PERIOD", 1_000);
-    let smith_cert_validity_period = get_env_u32("DUNITER_SMITH_CERT_VALIDITY_PERIOD", 1_000);
-    let smith_membership_period = get_env_u32("DUNITER_SMITH_MEMBERSHIP_PERIOD", 1_000);
+    let babe_epoch_duration = get_env("DUNITER_BABE_EPOCH_DURATION", 30) as u64;
+    let cert_validity_period = get_env("DUNITER_CERT_VALIDITY_PERIOD", 1_000);
+    let membership_period = get_env("DUNITER_MEMBERSHIP_PERIOD", 1_000);
+    let smith_cert_validity_period = get_env("DUNITER_SMITH_CERT_VALIDITY_PERIOD", 1_000);
+    let smith_membership_period = get_env("DUNITER_SMITH_MEMBERSHIP_PERIOD", 1_000);
     let ud_creation_period = get_env("DUNITER_UD_CREATION_PERIOD", 60_000);
     let ud_reeval_period = get_env("DUNITER_UD_REEEVAL_PERIOD", 1_200_000);
     let ud = 1_000;